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  1. #include <stdio.h>
  2. #include <math.h>
  3.  
  4.  
  5. double der(double x, double c[], int n)
  6. {
  7.     double d = 0;
  8.     for (int i = 0; i < n; i++) {
  9.         d *= x;
  10.         d += c[i];
  11.     }
  12.     return d;
  13. }
  14.  
  15. double der2(double x, double c[], int n)
  16. {
  17.     double d = 0;
  18.     for (int i = 0; i < n - 1; i++) {
  19.         d *= x;
  20.         d += (n - i - 1) * c[i];
  21.     }
  22.     return d;
  23. }
  24.  
  25. int main()
  26. {
  27.     double coeffs[] = { 3 * 3.0, 2 * 2.0, 1 * 4.0 };
  28.     double x = 1.0;
  29.     double d = der(x, coeffs, sizeof(coeffs) / sizeof(coeffs[0]));
  30.     printf("f'(%lf) = %lf\n", x, d);
  31.  
  32.     double coeffs2[] = { 3.0, 2.0, 4.0, 5.0 };
  33.     d = der2(x, coeffs2, sizeof(coeffs2) / sizeof(coeffs2[0]));
  34.     printf("f'(%lf) = %lf\n", x, d);
  35.     return 0;
  36. }
  37.  
Success #stdin #stdout 0s 1788KB
comments (?)
stdin 
Standard input is empty
stdout 
f'(1.000000) = 17.000000
f'(1.000000) = 17.000000
https://ideone.com/P8Qbg3
language:
C99 (gcc 8.3)
created:
12 years ago
visibility:
public

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