| 1 | #include "f2c.h" |
| 2 | |
| 3 | #ifdef KR_headers |
| 4 | VOID pow_zi(p, a, b) /* p = a**b */ |
| 5 | doublecomplex *p, *a; integer *b; |
| 6 | #else |
| 7 | extern void z_div(doublecomplex*, doublecomplex*, doublecomplex*); |
| 8 | void pow_zi(doublecomplex *p, doublecomplex *a, integer *b) /* p = a**b */ |
| 9 | #endif |
| 10 | { |
| 11 | integer n; |
| 12 | double t; |
| 13 | doublecomplex x; |
| 14 | static doublecomplex one = {1.0, 0.0}; |
| 15 | |
| 16 | n = *b; |
| 17 | p->r = 1; |
| 18 | p->i = 0; |
| 19 | |
| 20 | if(n == 0) |
| 21 | return; |
| 22 | if(n < 0) |
| 23 | { |
| 24 | n = -n; |
| 25 | z_div(&x, &one, a); |
| 26 | } |
| 27 | else |
| 28 | { |
| 29 | x.r = a->r; |
| 30 | x.i = a->i; |
| 31 | } |
| 32 | |
| 33 | for( ; ; ) |
| 34 | { |
| 35 | if(n & 01) |
| 36 | { |
| 37 | t = p->r * x.r - p->i * x.i; |
| 38 | p->i = p->r * x.i + p->i * x.r; |
| 39 | p->r = t; |
| 40 | } |
| 41 | if(n >>= 1) |
| 42 | { |
| 43 | t = x.r * x.r - x.i * x.i; |
| 44 | x.i = 2 * x.r * x.i; |
| 45 | x.r = t; |
| 46 | } |
| 47 | else |
| 48 | break; |
| 49 | } |
| 50 | } |