<![CDATA[
#include <stdio.h>
#include <math.h>
#include <chplot.h>
#include <numeric.h>
#define N 36
double func(double x) {
return x*sin(x)*cos(x);
}
int main() {
array double x[N], y[N], yprime[N];
double err, h;
int i;
class CPlot plot;
linspace(x, 0, 2*M_PI);
printf(" x derivative() value Cal. value\n");
// /* Specify the initial step h and return estimate error */
// yprime =derivatives(func,x,&err,0.8);
yprime =derivatives(func,x); /* use default step value and do not return err */
fevalarray(y,func,x);
for (i=0; i<2; i++)
printf("%12.6f %12.6f %12.6f\n",x[i],yprime[i],
(0.5*sin(2*x[i])+x[i]*cos(2*x[i])));
printf(" -------- --------- --------\n");
for (i=34; i<36; i++)
printf("%12.6f %12.6f %12.6f\n",x[i],yprime[i],
(0.5*sin(2*x[i])+x[i]*cos(2*x[i])));
plot.Label(PLOT_AXIS_X,"x");
plot.Label(PLOT_AXIS_Y,"f(x) & d(f(x))/dx");
plot.Data2D(x,y);
plot.Data2D(x,yprime);
plot.Legend("f(x)",0);
plot.Legend("d(f(x))/dx",1);
plot.Plotting();
}
]]>
<![CDATA[
x derivative() value Cal. value
0.000000 0.000000 0.000000
0.179520 0.343760 0.343760
-------- --------- --------
6.103666 5.538777 5.538777
6.283185 6.283185 6.283185
]]>