gnuplot.cpp

/**
 * This is the source code for a set of wrapper functions to make calls
 * to gnuplot. Gnuplot is a freely available, command-driven graphical
 * display tool for Unix. It compiles and works quite well on a number
 * of Unix flavours as well as other operating systems. The following
 * module enables sending display requests to gnuplot through simple
 * C/C++ calls.
 *
 * The module was adapted from the source code provided freely online
 * by N. Devillard, Revision 2.10, September 1998.
*/

#include "gnuplot.h"


/* Maximal size of a gnuplot command */
#define GP_CMD_SIZE     	2048

/* Maximal size of a plot title */
#define GP_TITLE_SIZE   	80

/* Maximal size for an equation */
#define GP_EQ_SIZE      	512

/* Maximal size of a name in the PATH */
#define PATH_MAXNAMESZ       4096

/* Define P_tmpdir if not defined (this is normally a POSIX symbol) */
#ifndef P_tmpdir
#define P_tmpdir "."
#endif


/**
 *@brief	Find out where a command lives in your PATH.
 *@param	pname Name of the program to look for.
 *@return	pointer to statically allocated character string.
 *
 * This is the C equivalent to the 'which' command in Unix. It parses
 * out your PATH environment variable to find out where a command
 * lives. The returned character string is statically allocated within
 * this function, i.e. there is no need to free it. Beware that the
 * contents of this string will change from one call to the next,
 * though (as all static variables in a function).

 * The input character string must be the name of a command without
 * prefixing path of any kind, i.e. only the command name. The returned
 * string is the path in which a command matching the same name was
 * found.

 * Examples (assuming there is a prog named 'hello' in the cwd):

 *@verbatim
 *gnuplot_get_program_path("hello") returns "."
 *gnuplot_get_program_path("ls") returns "/bin"
 *gnuplot_get_program_path("csh") returns "/usr/bin"
 *gnuplot_get_program_path("/bin/ls") returns NULL
 *@endverbatim
 */
char* gnuplot_get_program_path(char* pname) {
    int i, j, lg;
    char* path;
    static char buf[PATH_MAXNAMESZ];

    /* Trivial case: try in CWD */
    sprintf(buf, "./%s", pname);
    if (access(buf, X_OK)==0) {
        sprintf(buf, ".");
        return buf;
    }

    /* Try out in all paths given in the PATH variable */
    buf[0] = 0;
    path = getenv("PATH");
    if (path!=NULL) {
        for (i=0; path[i]; ) {
            for (j=i; (path[j]) && (path[j]!=':'); j++);
            lg = j - i;
            strncpy(buf, path + i, lg);
            if (lg == 0) buf[lg++] = '.';
            buf[lg++] = '/';
            strcpy(buf + lg, pname);
            if (access(buf, X_OK) == 0) {
                /* Found it! */
                break;
            }
            buf[0] = 0;
            i = j;
            if (path[i] == ':') i++;
        }
    }
    else
		fprintf(stderr, "PATH variable not set\n");

    /* If the buffer is still empty, the command was not found */
    if (buf[0] == 0) return NULL;

    /* Otherwise truncate the command name to yield path only */
    lg = strlen(buf) - 1;

    while (buf[lg]!='/') {
        buf[lg]=0;
        lg --;
    }
    buf[lg] = 0;
    return buf;
}



/**
 *@brief	Opens up a gnuplot session, ready to receive commands.
 *@return	Newly allocated gnuplot control structure.
 *
 * This opens up a new gnuplot session, ready for input. The struct
 * controlling a gnuplot session should remain opaque and only be
 * accessed through the provided functions.
 * The session must be closed using gnuplot_close().
 */
gnuplot_ctrl* gnuplot_init(void) {
    gnuplot_ctrl* handle;

    if (getenv("DISPLAY") == NULL)
        fprintf(stderr, "cannot find DISPLAY variable: is it set?\n");

	if (gnuplot_get_program_path((char*)"gnuplot")==NULL) {
		fprintf(stderr, "cannot find gnuplot in your PATH");
		return NULL;
	}

    /* Structure initialization */
    handle = (gnuplot_ctrl*)malloc(sizeof(gnuplot_ctrl));
    handle->nplots = 0;
    gnuplot_setstyle(handle, (char*)"points");
    handle->ntmp = 0;

    handle->gnucmd = popen("gnuplot", "w");
    if (handle->gnucmd == NULL) {
        fprintf(stderr, "error starting gnuplot\n");
        free(handle);
        return NULL;
    }
    return handle;
}


/**
 *@brief	Closes a gnuplot session previously opened by gnuplot_init()
 *@param	handle Gnuplot session control handle.
 *@return	void
 *
 * Kills the child PID and deletes all opened temporary files.
 * It is mandatory to call this function to close the handle, otherwise
 * temporary files are not cleaned and child process might survive.
 */
void gnuplot_close(gnuplot_ctrl* handle) {
    int i;
	
    if (pclose(handle->gnucmd) == -1) {
        fprintf(stderr, "problem closing communication to gnuplot\n");
        return;
    }
    if (handle->ntmp) {
        for (i=0; i<handle->ntmp; i++)
            remove(handle->to_delete[i]);
    }
    free(handle);
    return;
}


/**
 * @brief	Sends a command to an active gnuplot session.
 * @param	handle Gnuplot session control handle
 * @param	cmd    Command to send, same as a printf statement.
 *
 * This sends a string to an active gnuplot session, to be executed.
 * There is strictly no way to know if the command has been
 * successfully executed or not.
 * The command syntax is the same as printf.
 *
 * Examples:
 *
 * @code
 * gnuplot_cmd(g, "plot %d*x", 23.0);
 * gnuplot_cmd(g, "plot %g * cos(%g * x)", 32.0, -3.0);
 * @endcode
 *
 * Since the communication to the gnuplot process is run through
 * a standard Unix pipe, it is only unidirectional. This means that
 * it is not possible for this interface to query an error status
 * back from gnuplot.
 */
void gnuplot_cmd(gnuplot_ctrl*  handle, char*  cmd, ...) {
    va_list ap;
    char local_cmd[GP_CMD_SIZE];

    va_start(ap, cmd);
    vsprintf(local_cmd, cmd, ap);
    va_end(ap);

    strcat(local_cmd, "\n");

    fputs(local_cmd, handle->gnucmd);
    fflush(handle->gnucmd);
    return;
}


/**
 * @brief	Change the plotting style of a gnuplot session.
 * @param	h Gnuplot session control handle
 * @param	plot_style Plotting-style to use (character string)
 * @return	void
 *
 * The provided plotting style is a character string. It must be one of
 * the following:
 *
 * - lines
 * - points
 * - linespoints
 * - impulses
 * - dots
 * - steps
 * - errorbars
 * - boxes
 * - boxeserrorbars
 */
void gnuplot_setstyle(gnuplot_ctrl* h, char* plot_style) {
    if (strcmp(plot_style, "lines") &&
        strcmp(plot_style, "points") &&
        strcmp(plot_style, "linespoints") &&
        strcmp(plot_style, "impulses") &&
        strcmp(plot_style, "dots") &&
        strcmp(plot_style, "steps") &&
        strcmp(plot_style, "errorbars") &&
        strcmp(plot_style, "boxes") &&
        strcmp(plot_style, "boxerrorbars")) {
        fprintf(stderr, "warning: unknown requested style: using points\n");
        strcpy(h->pstyle, "points");
    }
    else
        strcpy(h->pstyle, plot_style);
    return;
}


/**
 * @brief	Sets the x label of a gnuplot session.
 * @param	h Gnuplot session control handle.
 * @param	label Character string to use for X label.
 * @return	void
 *
 * Sets the x label for a gnuplot session.
 */
void gnuplot_set_xlabel(gnuplot_ctrl* h, char* label) {
    char cmd[GP_CMD_SIZE];

    sprintf(cmd, "set xlabel \"%s\"", label);
    gnuplot_cmd(h, cmd);
    return;
}


/**
 * @brief	Sets the y label of a gnuplot session.
 * @param	h Gnuplot session control handle
 * @param	label Character string to use for Y label.
 * @return	void
 *
 * Sets the y label for a gnuplot session.
 */
void gnuplot_set_ylabel(gnuplot_ctrl* h, char* label)
{
    char cmd[GP_CMD_SIZE];

    sprintf(cmd, "set ylabel \"%s\"", label);
    gnuplot_cmd(h, cmd);
    return;
}


/**
 * @brief 	Sets the minimum and maximum y values for a gnuplot session
 * @param 	h Gnuplot session control handle
 * @param 	lower the minimum y value
 * @param 	upper the maximum y value
 */
void gnuplot_set_yrange(gnuplot_ctrl* h, int lower, int upper) {
	std::stringstream cmd;
	cmd << "set yrange [" << lower << ":" << upper << "]";
	gnuplot_cmd(h, (char*)cmd.str().c_str());
}


/**
 * @brief 	Sets the minimum and maximum y values for a gnuplot session
 * @param 	h Gnuplot session control handle
 * @param 	lower the minimum y value
 * @param 	upper the maximum y value
 */
void gnuplot_set_yrange(gnuplot_ctrl* h, float lower, float upper) {
	std::stringstream cmd;
	cmd << "set yrange [" << lower << ":" << upper << "]";
	gnuplot_cmd(h, (char*)cmd.str().c_str());
}


/**
 * @brief 	Sets the minimum and maximum y values for a gnuplot session
 * @param 	h Gnuplot session control handle
 * @param 	lower the minimum y value
 * @param 	upper the maximum y value
 */
void gnuplot_set_yrange(gnuplot_ctrl* h, double lower, double upper) {
	std::stringstream cmd;
	cmd << "set yrange [" << lower << ":" << upper << "]";
	gnuplot_cmd(h, (char*)cmd.str().c_str());
}


/**
 * @brief 	Sets the minimum and maximum x values for a gnuplot session
 * @param 	h Gnuplot session control handle
 * @param 	lower the minimum y value
 * @param 	upper the maximum y value
 */
void gnuplot_set_xrange(gnuplot_ctrl* h, int lower, int upper) {
	std::stringstream cmd;
	cmd << "set xrange [" << lower << ":" << upper << "]";
	gnuplot_cmd(h, (char*)cmd.str().c_str());
}


/**
 * @brief 	Sets the minimum and maximum x values for a gnuplot session
 * @param 	h Gnuplot session control handle
 * @param 	lower the minimum y value
 * @param 	upper the maximum y value
 */
void gnuplot_set_xrange(gnuplot_ctrl* h, float lower, float upper) {
	std::stringstream cmd;
	cmd << "set xrange [" << lower << ":" << upper << "]";
	gnuplot_cmd(h, (char*)cmd.str().c_str());
}


/**
 * @brief 	Sets the minimum and maximum x values for a gnuplot session
 * @param 	h Gnuplot session control handle
 * @param 	lower the minimum y value
 * @param 	upper the maximum y value
 */
void gnuplot_set_xrange(gnuplot_ctrl* h, double lower, double upper) {
	std::stringstream cmd;
	cmd << "set xrange [" << lower << ":" << upper << "]";
	gnuplot_cmd(h, (char*)cmd.str().c_str());
}


/**
 * @brief	Resets a gnuplot session (next plot will erase previous ones).
 * @param	h Gnuplot session control handle.
 * @return	void
 *
 * Resets a gnuplot session, i.e. the next plot will erase all previous
 * ones.
 */
void gnuplot_resetplot(gnuplot_ctrl* h) {

	int i;

	if (h->ntmp) {
        for (i=0; i<h->ntmp; i++)
            remove(h->to_delete[i]);
    }
    h->ntmp = 0;
    h->nplots = 0;
    return;
}


/**
 * @brief	Saves the current Gnuplot session as a pdf
 * @param 	h Gnuplot session control handle
 * @param	filename the name of the file the plot will be saved as
 */
void gnuplot_saveplot(gnuplot_ctrl* h, char* filename) {
	std::stringstream cmd;
	cmd << "set output \"" << filename << ".pdf\"";
	gnuplot_cmd(h, (char*)"set term pdf");
	gnuplot_cmd(h, (char*)cmd.str().c_str());
}



/**
 * @brief	Plots a 2d graph from a list of ints
 * @param	handle	Gnuplot session control handle.
 * @param	d		Array of ints.
 * @param	n		Number of values in the passed array.
 * @param	title	Title of the plot.
 * @return	void
 *
 * Plots out a 2d graph from a list of ints. The x-coordinate is the
 * index of the float in the list, the y coordinate is the int in
 * the list.
 *
 * Example:
 *
 * @code
 *  gnuplot_ctrl    *h;
 *   int          d[50];
 *   int             i;
 *
 *   h = gnuplot_init();
 *   for (i=0; i<50; i++) {
 *       d[i] = (int)(i*i);
 *   }
 *   gnuplot_plot_x(h, d, 50, "parabola");
 *   sleep(2);
 *   gnuplot_close(h);
 * @endcode
 */
void gnuplot_plot_x(gnuplot_ctrl* handle, int* d, int n, char* title) {
    int i;
	int tmpfd;
    char name[128];
    char cmd[GP_CMD_SIZE];
    char line[GP_CMD_SIZE];

	if (handle==NULL || d==NULL || (n<1)) return;

    /* Open one more temporary file? */
    if (handle->ntmp == GP_MAX_TMP_FILES - 1) {
        fprintf(stderr,
                "maximum # of temporary files reached (%d): cannot open more",
                GP_MAX_TMP_FILES);
        return;
    }

    /* Open temporary file for output   */
	sprintf(name, "%s/gnuplot-i-XXXXXX", P_tmpdir);
    if ((tmpfd=mkstemp(name))==-1) {
        fprintf(stderr,"cannot create temporary file: exiting plot");
        return;
    }

    /* Store file name in array for future deletion */
    strcpy(handle->to_delete[handle->ntmp], name);
    handle->ntmp ++;
    /* Write data to this file  */
    for (i=0; i<n; i++) {
		sprintf(line, "%d\n", d[i]);
		int writeRet = write(tmpfd, line, strlen(line));
		if (writeRet == -1)
			printf("Error writing data to a file in gnuplot_x");
    }
    close(tmpfd);

    /* Command to be sent to gnuplot    */
    if (handle->nplots > 0)
        strcpy(cmd, "replot");
    else
        strcpy(cmd, "plot");

    if (title == NULL)
        sprintf(line, "%s \"%s\" with %s", cmd, name, handle->pstyle);
    else
        sprintf(line, "%s \"%s\" title \"%s\" with %s", cmd, name,
                      title, handle->pstyle);

    /* send command to gnuplot  */
    gnuplot_cmd(handle, line);
    handle->nplots++;
    return;
}


/**
 * @brief	Plots a 2d graph from a list of floats
 * @param	handle	Gnuplot session control handle.
 * @param	d		Array of floats.
 * @param	n		Number of values in the passed array.
 * @param	title	Title of the plot.
 * @return	void
 *
 * Plots out a 2d graph from a list of floats. The x-coordinate is the
 * index of the float in the list, the y coordinate is the float in
 * the list.
 *
 * Example:
 *
 * @code
 *  gnuplot_ctrl    *h;
 *   float          d[50];
 *   int             i;
 *
 *   h = gnuplot_init();
 *   for (i=0; i<50; i++) {
 *       d[i] = (float)(i*i);
 *   }
 *   gnuplot_plot_x(h, d, 50, "parabola");
 *   sleep(2);
 *   gnuplot_close(h);
 * @endcode
 */
void gnuplot_plot_x(gnuplot_ctrl* handle, float* d, int n, char* title) {
    int i;
	int tmpfd;
    char name[128];
    char cmd[GP_CMD_SIZE];
    char line[GP_CMD_SIZE];

	if (handle==NULL || d==NULL || (n<1)) return;

    /* Open one more temporary file? */
    if (handle->ntmp == GP_MAX_TMP_FILES - 1) {
        fprintf(stderr,
                "maximum # of temporary files reached (%d): cannot open more",
                GP_MAX_TMP_FILES);
        return;
    }

    /* Open temporary file for output   */
	sprintf(name, "%s/gnuplot-i-XXXXXX", P_tmpdir);
    if ((tmpfd=mkstemp(name))==-1) {
        fprintf(stderr,"cannot create temporary file: exiting plot");
        return;
    }

    /* Store file name in array for future deletion */
    strcpy(handle->to_delete[handle->ntmp], name);
    handle->ntmp ++;
    /* Write data to this file  */
    for (i=0; i<n; i++) {
		sprintf(line, "%g\n", d[i]);
		int writeRet = write(tmpfd, line, strlen(line));
		if (writeRet == -1)
			printf("Error writing data to a file in gnuplot_x");
    }
    close(tmpfd);

    /* Command to be sent to gnuplot    */
    if (handle->nplots > 0)
        strcpy(cmd, "replot");
    else
        strcpy(cmd, "plot");

    if (title == NULL)
        sprintf(line, "%s \"%s\" with %s", cmd, name, handle->pstyle);
    else
        sprintf(line, "%s \"%s\" title \"%s\" with %s", cmd, name,
                      title, handle->pstyle);

    /* send command to gnuplot  */
    gnuplot_cmd(handle, line);
    handle->nplots++;
    return;
}


/**
 * @brief	Plots a 2d graph from a list of doubles
 * @param	handle	Gnuplot session control handle.
 * @param	d		Array of doubles.
 * @param	n		Number of values in the passed array.
 * @param	title	Title of the plot.
 * @return	void
 *
 * Plots out a 2d graph from a list of double. The x-coordinate is the
 * index of the double in the list, the y coordinate is the double in
 * the list.
 *
 * Example:
 *
 * @code
 *  gnuplot_ctrl    *h;
 *   double          d[50];
 *   int             i;
 *
 *   h = gnuplot_init();
 *   for (i=0; i<50; i++) {
 *       d[i] = (double)(i*i);
 *   }
 *   gnuplot_plot_x(h, d, 50, "parabola");
 *   sleep(2);
 *   gnuplot_close(h);
 * @endcode
 */
void gnuplot_plot_x(gnuplot_ctrl* handle, double* d, int n, char* title) {
    int i;
	int tmpfd;
    char name[128];
    char cmd[GP_CMD_SIZE];
    char line[GP_CMD_SIZE];

	if (handle==NULL || d==NULL || (n<1)) return;

    /* Open one more temporary file? */
    if (handle->ntmp == GP_MAX_TMP_FILES - 1) {
        fprintf(stderr,
                "maximum # of temporary files reached (%d): cannot open more",
                GP_MAX_TMP_FILES);
        return;
    }

    /* Open temporary file for output   */
	sprintf(name, "%s/gnuplot-i-XXXXXX", P_tmpdir);
    if ((tmpfd=mkstemp(name))==-1) {
        fprintf(stderr,"cannot create temporary file: exiting plot");
        return;
    }

    /* Store file name in array for future deletion */
    strcpy(handle->to_delete[handle->ntmp], name);
    handle->ntmp ++;
    /* Write data to this file  */
    for (i=0; i<n; i++) {
		sprintf(line, "%f\n", d[i]);
		int writeRet = write(tmpfd, line, strlen(line));
		if (writeRet == -1)
			printf("Error writing data to a file in gnuplot_x");
    }
    close(tmpfd);

    /* Command to be sent to gnuplot    */
    if (handle->nplots > 0)
        strcpy(cmd, "replot");
    else
        strcpy(cmd, "plot");
    
    if (title == NULL)
        sprintf(line, "%s \"%s\" with %s", cmd, name, handle->pstyle);
    else
        sprintf(line, "%s \"%s\" title \"%s\" with %s", cmd, name,
                      title, handle->pstyle);

    /* send command to gnuplot  */
    gnuplot_cmd(handle, line);
    handle->nplots++;
    return;
}


/**
 * @brief	Plot a 2d graph from a list of points.
 * @param	handle		Gnuplot session control handle.
 * @param	x			Pointer to a list of x coordinates.
 * @param	y			Pointer to a list of y coordinates.
 * @param	n			Number of doubles in x (assumed the same as in y).
 * @param	title		Title of the plot.
 * @return	void
 *
 * Plots out a 2d graph from a list of points. Provide points through a list
 * of x and a list of y coordinates. Both provided arrays are assumed to
 * contain the same number of values.
 *
 * @code
 *   gnuplot_ctrl    *h;
 *	 int			x[50];
 *	 int			y[50];
 *   int             i;
 *
 *    h = gnuplot_init();
 *    for (i=0; i<50; i++) {
 *        x[i] = (int)(i)/10.0;
 *        y[i] = x[i] * x[i];
 *    }
 *    gnuplot_plot_xy(h, x, y, 50, "parabola");
 *    sleep(2);
 *    gnuplot_close(h);
 *  @endcode
 */
void gnuplot_plot_xy(gnuplot_ctrl* handle, int* x, int* y,
											int n, char* title) {
    int i;
	int	tmpfd;
    char name[128];
    char cmd[GP_CMD_SIZE];
    char line[GP_CMD_SIZE];

	if (handle==NULL || x==NULL || y==NULL || (n<1)) return;

    /* Open one more temporary file? */
    if (handle->ntmp == GP_MAX_TMP_FILES - 1) {
        fprintf(stderr,
                "maximum # of temporary files reached (%d): cannot open more",
                GP_MAX_TMP_FILES);
        return;
    }

    /* Open temporary file for output   */
	sprintf(name, "%s/gnuplot-i-XXXXXX", P_tmpdir);
    if ((tmpfd=mkstemp(name))==-1) {
        fprintf(stderr,"cannot create temporary file: exiting plot");
        return;
    }
    /* Store file name in array for future deletion */
    strcpy(handle->to_delete[handle->ntmp], name);
    handle->ntmp ++;

    /* Write data to this file  */
    for (i=0; i<n; i++) {
        sprintf(line, "%d %d\n", x[i], y[i]);
		int writeRet = write(tmpfd, line, strlen(line));
		if (writeRet == -1)
			printf("Error writing data to a file in gnuplot_xy");
    }
    close(tmpfd);

    /* Command to be sent to gnuplot    */
    if (handle->nplots > 0)
        strcpy(cmd, "replot");
    else
        strcpy(cmd, "plot");

    if (title == NULL)
        sprintf(line, "%s \"%s\" with %s", cmd, name, handle->pstyle);
    else
    	sprintf(line, "%s \"%s\" title \"%s\" with %s", cmd, name,
                      title, handle->pstyle);

    /* send command to gnuplot  */
    gnuplot_cmd(handle, line);

    handle->nplots++;
    return;
}


/**
 * @brief	Plot a 2d graph from a list of points.
 * @param	handle		Gnuplot session control handle.
 * @param	x			Pointer to a list of x coordinates.
 * @param	y			Pointer to a list of y coordinates.
 * @param	n			Number of doubles in x (assumed the same as in y).
 * @param	title		Title of the plot.
 * @return	void
 *
 * Plots out a 2d graph from a list of points. Provide points through a list
 * of x and a list of y coordinates. Both provided arrays are assumed to
 * contain the same number of values.
 *
 * @code
 *   gnuplot_ctrl    *h;
 *	 float			x[50];
 *	 float			y[50];
 *   int             i;
 *
 *    h = gnuplot_init();
 *    for (i=0; i<50; i++) {
 *        x[i] = (float)(i)/10.0;
 *        y[i] = x[i] * x[i];
 *    }
 *    gnuplot_plot_xy(h, x, y, 50, "parabola");
 *    sleep(2);
 *    gnuplot_close(h);
 *  @endcode
 */
void gnuplot_plot_xy(gnuplot_ctrl* handle, float* x, float* y,
											int n, char* title) {
    int i;
	int	tmpfd;
    char name[128];
    char cmd[GP_CMD_SIZE];
    char line[GP_CMD_SIZE];

	if (handle==NULL || x==NULL || y==NULL || (n<1)) return;

    /* Open one more temporary file? */
    if (handle->ntmp == GP_MAX_TMP_FILES - 1) {
        fprintf(stderr,
                "maximum # of temporary files reached (%d): cannot open more",
                GP_MAX_TMP_FILES);
        return;
    }

    /* Open temporary file for output   */
	sprintf(name, "%s/gnuplot-i-XXXXXX", P_tmpdir);
    if ((tmpfd=mkstemp(name))==-1) {
        fprintf(stderr,"cannot create temporary file: exiting plot");
        return;
    }
    /* Store file name in array for future deletion */
    strcpy(handle->to_delete[handle->ntmp], name);
    handle->ntmp ++;

    /* Write data to this file  */
    for (i=0; i<n; i++) {
        sprintf(line, "%g %g\n", x[i], y[i]);
		int writeRet = write(tmpfd, line, strlen(line));
		if (writeRet == -1)
			printf("Error writing data to a file in gnuplot_xy");
    }
    close(tmpfd);

    /* Command to be sent to gnuplot    */
    if (handle->nplots > 0)
        strcpy(cmd, "replot");
    else
        strcpy(cmd, "plot");
    
    if (title == NULL)
        sprintf(line, "%s \"%s\" with %s", cmd, name, handle->pstyle);
    else
    	sprintf(line, "%s \"%s\" title \"%s\" with %s", cmd, name,
                      title, handle->pstyle);

    /* send command to gnuplot  */
    gnuplot_cmd(handle, line);

    handle->nplots++;
    return;
}


/**
 * @brief	Plot a 2d graph from a list of points.
 * @param	handle		Gnuplot session control handle.
 * @param	x			Pointer to a list of x coordinates.
 * @param	y			Pointer to a list of y coordinates.
 * @param	n			Number of doubles in x (assumed the same as in y).
 * @param	title		Title of the plot.
 * @return	void
 *
 * Plots out a 2d graph from a list of points. Provide points through a list
 * of x and a list of y coordinates. Both provided arrays are assumed to
 * contain the same number of values.
 *
 * @code
 *   gnuplot_ctrl    *h;
 *	 double			x[50];
 *	 double			y[50];
 *   int             i;
 *
 *    h = gnuplot_init();
 *    for (i=0; i<50; i++) {
 *        x[i] = (float)(i)/10.0;
 *        y[i] = x[i] * x[i];
 *    }
 *    gnuplot_plot_xy(h, x, y, 50, "parabola");
 *    sleep(2);
 *    gnuplot_close(h);
 *  @endcode
 */
void gnuplot_plot_xy(gnuplot_ctrl* handle, double* x, double* y,
											int n, char* title) {
    int i;
	int	tmpfd;
    char name[128];
    char cmd[GP_CMD_SIZE];
    char line[GP_CMD_SIZE];

	if (handle==NULL || x==NULL || y==NULL || (n<1)) return;

    /* Open one more temporary file? */
    if (handle->ntmp == GP_MAX_TMP_FILES - 1) {
        fprintf(stderr,
                "maximum # of temporary files reached (%d): cannot open more",
                GP_MAX_TMP_FILES);
        return;
    }

    /* Open temporary file for output   */
	sprintf(name, "%s/gnuplot-i-XXXXXX", P_tmpdir);
    if ((tmpfd=mkstemp(name))==-1) {
        fprintf(stderr,"cannot create temporary file: exiting plot");
        return;
    }
    /* Store file name in array for future deletion */
    strcpy(handle->to_delete[handle->ntmp], name);
    handle->ntmp ++;

    /* Write data to this file  */
    for (i=0; i<n; i++) {
        sprintf(line, "%f %f\n", x[i], y[i]);
		int writeRet = write(tmpfd, line, strlen(line));
		if (writeRet == -1)
			printf("Error writing data to a file in gnuplot_xy");
    }
    close(tmpfd);

    /* Command to be sent to gnuplot    */
    if (handle->nplots > 0)
        strcpy(cmd, "replot");
    else
        strcpy(cmd, "plot");

    if (title == NULL)
        sprintf(line, "%s \"%s\" with %s", cmd, name, handle->pstyle);
    else
    	sprintf(line, "%s \"%s\" title \"%s\" with %s", cmd, name,
                      title, handle->pstyle);

    /* send command to gnuplot  */
    gnuplot_cmd(handle, line);

    handle->nplots++;
    return;
}


/**
 * @brief	Open a new session, plot a signal, close the session.
 * @param	title	Plot title
 * @param	style	Plot style
 * @param	label_x	Label for X
 * @param	label_y	Label for Y
 * @param	x		Array of X coordinates
 * @param	y		Array of Y coordinates (can be NULL)
 * @param	n		Number of values in x and y.
 * @return
 *
 *  This function opens a new gnuplot session, plots the provided
 *  signal as an X or XY signal depending on a provided y, waits for
 *  a carriage return on stdin and closes the session.
 *
 * It is Ok to provide an empty title, empty style, or empty labels for
 * X and Y. Defaults are provided in this case.
 */
void gnuplot_plot_once(char* title, char* style, char* label_x, char* label_y,
												int* x, int* y, int n) {
	gnuplot_ctrl* handle;

	if (x==NULL || n<1)
		return;

	if ((handle = gnuplot_init()) == NULL)
		return;

	if (style!=NULL)
		gnuplot_setstyle(handle, style);
	else
		gnuplot_setstyle(handle, (char*)"lines");

	if (label_x!=NULL)
		gnuplot_set_xlabel(handle, label_x);
	else
		gnuplot_set_xlabel(handle, (char*)"X");

	if (label_y!=NULL)
		gnuplot_set_ylabel(handle, label_y);
	else
		gnuplot_set_ylabel(handle, (char*)"Y");

	if (y==NULL)
		gnuplot_plot_x(handle, x, n, title);
	else
		gnuplot_plot_xy(handle, x, y, n, title);

	printf("press ENTER to continue\n");
	while (getchar()!='\n') {}
	gnuplot_close(handle);
	return;
}


/**
 * @brief	Open a new session, plot a signal, close the session.
 * @param	title	Plot title
 * @param	style	Plot style
 * @param	label_x	Label for X
 * @param	label_y	Label for Y
 * @param	x		Array of X coordinates
 * @param	y		Array of Y coordinates (can be NULL)
 * @param	n		Number of values in x and y.
 * @return
 *
 *  This function opens a new gnuplot session, plots the provided
 *  signal as an X or XY signal depending on a provided y, waits for
 *  a carriage return on stdin and closes the session.
 *
 * It is Ok to provide an empty title, empty style, or empty labels for
 * X and Y. Defaults are provided in this case.
 */
void gnuplot_plot_once(char* title, char* style, char* label_x, char* label_y,
												float* x, float* y, int n) {
	gnuplot_ctrl* handle;

	if (x==NULL || n<1)
		return;

	if ((handle = gnuplot_init()) == NULL)
		return;

	if (style!=NULL)
		gnuplot_setstyle(handle, style);
	else
		gnuplot_setstyle(handle, (char*)"lines");

	if (label_x!=NULL)
		gnuplot_set_xlabel(handle, label_x);
	else
		gnuplot_set_xlabel(handle, (char*)"X");

	if (label_y!=NULL)
		gnuplot_set_ylabel(handle, label_y);
	else
		gnuplot_set_ylabel(handle, (char*)"Y");

	if (y==NULL)
		gnuplot_plot_x(handle, x, n, title);
	else
		gnuplot_plot_xy(handle, x, y, n, title);

	printf("press ENTER to continue\n");
	while (getchar()!='\n') {}
	gnuplot_close(handle);
	return;
}


/**
 * @brief	Open a new session, plot a signal, close the session.
 * @param	title	Plot title
 * @param	style	Plot style
 * @param	label_x	Label for X
 * @param	label_y	Label for Y
 * @param	x		Array of X coordinates
 * @param	y		Array of Y coordinates (can be NULL)
 * @param	n		Number of values in x and y.
 * @return
 *
 *  This function opens a new gnuplot session, plots the provided
 *  signal as an X or XY signal depending on a provided y, waits for
 *  a carriage return on stdin and closes the session.
 *
 * It is Ok to provide an empty title, empty style, or empty labels for
 * X and Y. Defaults are provided in this case.
 */
void gnuplot_plot_once(char* title, char* style, char* label_x, char* label_y,
												double* x, double* y, int n) {
	gnuplot_ctrl* handle;

	if (x==NULL || n<1)
		return;

	if ((handle = gnuplot_init()) == NULL)
		return;

	if (style!=NULL)
		gnuplot_setstyle(handle, style);
	else
		gnuplot_setstyle(handle, (char*)"lines");

	if (label_x!=NULL)
		gnuplot_set_xlabel(handle, label_x);
	else
		gnuplot_set_xlabel(handle, (char*)"X");

	if (label_y!=NULL)
		gnuplot_set_ylabel(handle, label_y);
	else
		gnuplot_set_ylabel(handle, (char*)"Y");

	if (y==NULL)
		gnuplot_plot_x(handle, x, n, title);
	else
		gnuplot_plot_xy(handle, x, y, n, title);

	printf("press ENTER to continue\n");
	while (getchar()!='\n') {}
	gnuplot_close(handle);
	return;
}


/**
 *  @brief	Plot a slope on a gnuplot session.
 *  @param	handle		Gnuplot session control handle.
 *  @param	a			Slope.
 *  @param	b			Intercept.
 *  @param	title		Title of the plot.
 *  @return	void
 *
 *  Plot a slope on a gnuplot session. The provided slope has an
 *  equation of the form y=ax+b
 *
 *  Example:
 *
 * @code
 *   gnuplot_ctrl    *   h;
 *   float              a, b;
 *
 *   h = gnuplot_init();
 *   gnuplot_plot_slope(h, 1.0, 0.0, "unity slope");
 *   sleep(2);
 *   gnuplot_close(h);
 * @endcode
 */
void gnuplot_plot_slope(gnuplot_ctrl* handle, float a, float b, char* title) {

	char stitle[GP_TITLE_SIZE];
    char cmd[GP_CMD_SIZE];

    if (title == NULL)
        strcpy(stitle, "no title");
    else
        strcpy(stitle, title);

    if (handle->nplots > 0)
        sprintf(cmd, "replot %g * x + %g title \"%s\" with %s",
                      a, b, title, handle->pstyle);
    else
        sprintf(cmd, "plot %g * x + %g title \"%s\" with %s",
                      a, b, title, handle->pstyle);

    gnuplot_cmd(handle, cmd);
    handle->nplots++;
    return;
}


/**
 * @brief	Plot a curve of given equation y=f(x).
 * @param	h			Gnuplot session control handle.
 * @param	equation	Equation to plot.
 * @param	title		Title of the plot.
 * @return	void
 *
 *  Plots out a curve of given equation. The general form of the
 * equation is y=f(x), you only provide the f(x) side of the equation.
 *
 * Example:
 *
 * @code
 *       gnuplot_ctrl    *h;
 *       char            eq[80];
 *
 *       h = gnuplot_init();
 *       strcpy(eq, "sin(x) * cos(2*x)");
 *       gnuplot_plot_equation(h, eq, "sine wave", normal);
 *       gnuplot_close(h);
 * @endcode
 */
void gnuplot_plot_equation(gnuplot_ctrl* h, char* equation, char* title) {

	char cmd[GP_CMD_SIZE];
    char plot_str[GP_EQ_SIZE];
    char title_str[GP_TITLE_SIZE];

    if (title == NULL)
        strcpy(title_str, "no title");
    else
        strcpy(title_str, title);

    if (h->nplots > 0)
        strcpy(plot_str, "replot");
    else
        strcpy(plot_str, "plot");

    sprintf(cmd, "%s %s title \"%s\" with %s", 
                  plot_str, equation, title_str, h->pstyle);
    gnuplot_cmd(h, cmd);
    h->nplots++;
    return;
}


/**
 * @brief Plots a 3D scatter point from 3 arrays of ints
 * @param handle 	Gnuplot session handle
 * @param x			array of ints
 * @param y			array of ints
 * @param z			array of ints
 * @param n			number of ints in each array x, y, and z
 * @param title		the title for the plot
 */
void gnuplot_plot_xyz(gnuplot_ctrl* handle, int* x, int* y, int* z,
													int n, char* title) {
    int i;
	int	tmpfd;
    char name[128];
    char cmd[GP_CMD_SIZE];
    char line[GP_CMD_SIZE];

	if (handle==NULL || x==NULL || y==NULL || (n<1)) return;

    /* Open one more temporary file? */
    if (handle->ntmp == GP_MAX_TMP_FILES - 1) {
        fprintf(stderr,
                "maximum # of temporary files reached (%d): cannot open more",
                GP_MAX_TMP_FILES);
        return;
    }

    /* Open temporary file for output   */
	sprintf(name, "%s/gnuplot-i-XXXXXX", P_tmpdir);
    if ((tmpfd=mkstemp(name))==-1) {
        fprintf(stderr,"cannot create temporary file: exiting plot");
        return;
    }
    /* Store file name in array for future deletion */
    strcpy(handle->to_delete[handle->ntmp], name);
    handle->ntmp ++;

    /* Write data to this file  */
    for (i=0; i<n; i++) {
        sprintf(line, "%d %d %d\n", x[i], y[i], z[i]);
		int writeRet = write(tmpfd, line, strlen(line));
		if (writeRet == -1)
			printf("Error writing data to a file in gnuplot_xyz");
    }
    close(tmpfd);

    /* Command to be sent to gnuplot    */
    if (handle->nplots > 0)
        strcpy(cmd, "replot");
    else {
    	strcpy(cmd, "dgrid3d");
        strcpy(cmd, "splot");
    }

    if (title == NULL)
        sprintf(line, "%s \"%s\" with %s", cmd, name, handle->pstyle);
    else
        sprintf(line, "%s \"%s\" title \"%s\" with %s", cmd, name,
                      title, handle->pstyle);

    /* send command to gnuplot  */
    gnuplot_cmd(handle, line);
    handle->nplots++;
    return;
}


/**
 * @brief Plots a 3D scatter point from 3 arrays of floats
 * @param handle 	Gnuplot session handle
 * @param x			array of floats
 * @param y			array of floats
 * @param z			array of floats
 * @param n			number of floats in each array x, y, and z
 * @param title		the title for the plot
 */
void gnuplot_plot_xyz(gnuplot_ctrl* handle, float* x, float* y, float* z,
													int n, char* title) {
    int i;
	int	tmpfd;
    char name[128];
    char cmd[GP_CMD_SIZE];
    char line[GP_CMD_SIZE];

	if (handle==NULL || x==NULL || y==NULL || (n<1)) return;

    /* Open one more temporary file? */
    if (handle->ntmp == GP_MAX_TMP_FILES - 1) {
        fprintf(stderr,
                "maximum # of temporary files reached (%d): cannot open more",
                GP_MAX_TMP_FILES);
        return;
    }

    /* Open temporary file for output   */
	sprintf(name, "%s/gnuplot-i-XXXXXX", P_tmpdir);
    if ((tmpfd=mkstemp(name))==-1) {
        fprintf(stderr,"cannot create temporary file: exiting plot");
        return;
    }
    /* Store file name in array for future deletion */
    strcpy(handle->to_delete[handle->ntmp], name);
    handle->ntmp ++;

    /* Write data to this file  */
    for (i=0; i<n; i++) {
        sprintf(line, "%g %g %g\n", x[i], y[i], z[i]);
		int writeRet = write(tmpfd, line, strlen(line));
		if (writeRet == -1)
			printf("Error writing data to a file in gnuplot_xyz");
    }
    close(tmpfd);

    /* Command to be sent to gnuplot    */
    if (handle->nplots > 0)
        strcpy(cmd, "replot");
    else {
    	strcpy(cmd, "dgrid3d");
        strcpy(cmd, "splot");
    }

    if (title == NULL)
        sprintf(line, "%s \"%s\" with %s", cmd, name, handle->pstyle);
    else
        sprintf(line, "%s \"%s\" title \"%s\" with %s", cmd, name,
                      title, handle->pstyle);

    /* send command to gnuplot  */
    gnuplot_cmd(handle, line);
    handle->nplots++;
    return;
}


/**
 * @brief Plots a 3D scatter point from 3 arrays of doubles
 * @param handle 	Gnuplot session handle
 * @param x			array of doubles
 * @param y			array of doubles
 * @param z			array of doubles
 * @param n			number of doubles in each array x, y, and z
 * @param title		the title for the plot
 */
void gnuplot_plot_xyz(gnuplot_ctrl* handle, double* x, double* y, double* z,
													int n, char* title) {
    int i;
	int	tmpfd;
    char name[128];
    char cmd[GP_CMD_SIZE];
    char line[GP_CMD_SIZE];

	if (handle==NULL || x==NULL || y==NULL || (n<1)) return;

    /* Open one more temporary file? */
    if (handle->ntmp == GP_MAX_TMP_FILES - 1) {
        fprintf(stderr,
                "maximum # of temporary files reached (%d): cannot open more",
                GP_MAX_TMP_FILES);
        return;
    }

    /* Open temporary file for output   */
	sprintf(name, "%s/gnuplot-i-XXXXXX", P_tmpdir);
    if ((tmpfd=mkstemp(name))==-1) {
        fprintf(stderr,"cannot create temporary file: exiting plot");
        return;
    }
    /* Store file name in array for future deletion */
    strcpy(handle->to_delete[handle->ntmp], name);
    handle->ntmp ++;

    /* Write data to this file  */
    for (i=0; i<n; i++) {
        sprintf(line, "%f %f %f\n", x[i], y[i], z[i]);
		int writeRet = write(tmpfd, line, strlen(line));
		if (writeRet == -1)
			printf("Error writing data to a file in gnuplot_xyz");
    }
    close(tmpfd);

    /* Command to be sent to gnuplot    */
    if (handle->nplots > 0)
        strcpy(cmd, "replot");
    else {
    	strcpy(cmd, "dgrid3d");
        strcpy(cmd, "splot");
    }

    if (title == NULL)
        sprintf(line, "%s \"%s\" with %s", cmd, name, handle->pstyle);
    else
        sprintf(line, "%s \"%s\" title \"%s\" with %s", cmd, name,
                      title, handle->pstyle);

    /* send command to gnuplot  */
    gnuplot_cmd(handle, line);
    handle->nplots++;
    return;
}