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55 lines
784 B
C
55 lines
784 B
C
#include "f2c.h"
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#ifdef KR_headers
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VOID pow_zi(p, a, b) /* p = a**b */
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doublecomplex *p, *a; integer *b;
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#else
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extern void z_div(doublecomplex*, doublecomplex*, doublecomplex*);
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void pow_zi(doublecomplex *p, doublecomplex *a, integer *b) /* p = a**b */
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#endif
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{
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integer n;
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unsigned long u;
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double t;
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doublecomplex q, x;
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static doublecomplex one = {1.0, 0.0};
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n = *b;
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q.r = 1;
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q.i = 0;
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if(n == 0)
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goto done;
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if(n < 0)
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{
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n = -n;
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z_div(&x, &one, a);
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}
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else
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{
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x.r = a->r;
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x.i = a->i;
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}
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for(u = n; ; )
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{
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if(u & 01)
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{
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t = q.r * x.r - q.i * x.i;
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q.i = q.r * x.i + q.i * x.r;
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q.r = t;
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}
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if(u >>= 1)
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{
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t = x.r * x.r - x.i * x.i;
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x.i = 2 * x.r * x.i;
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x.r = t;
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}
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else
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break;
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}
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done:
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p->i = q.i;
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p->r = q.r;
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}
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