int main(void)
{
int i,j,mval;
float a=(-PIO2),b=PIO2,poly,x,y;
float c[NVAL],d[NVAL];
chebft(a,b,c,NVAL,func);
for (;;) {
printf("\nHow many terms in Chebyshev evaluation?\n");
printf("Enter n between 6 and %2d. (n=0 to end).\n",NVAL);
scanf("%d",&mval);
if ((mval <= 0) || (mval > NVAL)) break;
chebpc(c,d,mval);
/* Test polynomial */
printf("\n%9s %14s %14s\n","x","actual","polynomial");
for (i = -8;i<=8;i++) {
x=i*PIO2/10.0;
y=(x-0.5*(b+a))/(0.5*(b-a));
poly=d[mval-1];
for (j=mval-2;j>=0;j--) poly=poly*y+d[j];
printf("%12.6f %12.6f %12.6f\n",x,func(x),poly);
}
}
return 0;
}
int main(void)
{
float a=(-PIO2),b=PIO2,dum,f;
float t0,t1,term,x,y,c[NVAL];
int i,j,mval;
chebft(a,b,c,NVAL,func);
/* test result */
for (;;) {
printf("\nHow many terms in Chebyshev evaluation?\n");
printf("Enter n between 6 and %2d. (n=0 to end).\n",NVAL);
scanf("%d",&mval);
if ((mval <= 0) || (mval > NVAL)) break;
printf("\n%9s %14s %16s\n","x","actual","chebyshev fit");
for (i = -8;i<=8;i++) {
x=i*PIO2/10.0;
y=(x-0.5*(b+a))/(0.5*(b-a));
/* Evaluate Chebyshev polynomial without CHEBEV */
t0=1.0;
t1=y;
f=c[1]*t1+c[0]*0.5;
for (j=2;j<mval;j++) {
dum=t1;
t1=2.0*y*t1-t0;
t0=dum;
term=c[j]*t1;
f += term;
}
printf("%12.6f %12.6f %12.6f\n",x,func(x),f);
}
}
return 0;
}