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#include <stdio.h>
#define NPT 100 /* Number of data points */
#define NTERM 5 /* Number of term */
int main() {
int i,j,status;
array double u[NPT],x[NPT],y[NPT],a[NTERM];
/* Create a data set of NTERM order polynomial with uniform random deviation*/
linspace(x,0.1,0.1*NPT);
y = 8*x.*x.*x.*x + 5*x.*x.*x + 3*x.*x + 6*x + (array double[NPT])(7);
/* put uniform random deviation on data set */
urand(u);
y += 0.1*u;
status=polyfit(a,x,y);
if(status) printf("Abnormal fit");
printf("\n%11s\n","Coefficients");
for (i=0;i<NTERM;i++)
printf(" a[%1d] = %8.6f \n",i,a[i]);
printf("y = %f at x = %f\n", polyeval(a, 2.0), 2.0);
}
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Coefficients
a[0] = 8.000048
a[1] = 4.999537
a[2] = 2.998743
a[3] = 6.015915
a[4] = 7.033637
y = 199.057500 at x = 2.000000
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