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/* plot.c - example of unix pipe. Calls gnuplot graph drawing package to draw
graphs from within a C program. Info is piped to gnuplot */
/* Creates 2 pipes one will draw graphs of y=0.5 and y = random 0-1.0 */
/* the other graphs of y = sin (1/x) and y = sin x */
/* c89 -o plot plot.c plotter.c - ON DECS */
/* acc -o plot plot.c plotter.c - ON SUNS */
#include "externals.h"
#include <signal.h>
#define DEG_TO_RAD(x) (x*180/M_PI)
double drand48();
void quit();
FILE *fp1, *fp2, *fp3, *fp4, *fopen();
main()
{ float i;
float y1,y2,y3,y4;
/* open files which will store plot data */
if ( ((fp1 = fopen("plot11.dat","w")) == NULL) ||
((fp2 = fopen("plot12.dat","w")) == NULL) ||
((fp3 = fopen("plot21.dat","w")) == NULL) ||
((fp4 = fopen("plot22.dat","w")) == NULL) )
{ printf("Error can't open one or more data files\n");
exit(1);
}
signal(SIGINT,quit); /* trap ctrl-c call quit fn */
StartPlot();
y1 = 0.5;
srand48(1); /* set seed */
for (i=0;;i+=0.01) /* increment i forever use ctrl-c to quit prog */
{ y2 = (float) drand48();
if (i == 0.0)
y3 = 0.0;
else
y3 = sin(DEG_TO_RAD(1.0/i));
y4 = sin(DEG_TO_RAD(i));
/* load files */
fprintf(fp1,"%f %f\n",i,y1);
fprintf(fp2,"%f %f\n",i,y2);
fprintf(fp3,"%f %f\n",i,y3);
fprintf(fp4,"%f %f\n",i,y4);
/* make sure buffers flushed so that gnuplot reads up to data file */
fflush(fp1);
fflush(fp2);
fflush(fp3);
fflush(fp4);
/* plot graph */
PlotOne();
usleep(250); /* sleep for short time */
}
}
void quit()
{ printf("\nctrl-c caught:\n Shutting down pipes\n");
StopPlot();
printf("closing data files\n");
fclose(fp1);
fclose(fp2);
fclose(fp3);
fclose(fp4);
printf("deleting data files\n");
RemoveDat();
}