45 lines
780 B
C
45 lines
780 B
C
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/* ctanh.c */
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/*
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Contributed by Danny Smith
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2003-10-20
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*/
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#include <math.h>
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#include <complex.h>
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#include <errno.h>
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/*
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ctanh (x + I * y) = (sinh (2 * x) + sin (2 * y) * I )
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/ (cosh (2 * x) + cos (2 * y)) .
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*/
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double complex
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ctanh (double complex Z)
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{
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double complex Res;
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double two_R = 2.0 * __real__ Z;
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double two_I = 2.0 * __imag__ Z;
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double denom = cosh (two_R) + cos (two_I);
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if (denom == 0.0)
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{
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errno = ERANGE;
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__real__ Res = HUGE_VAL;
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__imag__ Res = HUGE_VAL;
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}
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else if ( isinf (denom))
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{
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errno = ERANGE;
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__real__ Res = two_R > 0 ? 1.0 : -1.0;
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__imag__ Res = 0.0;
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}
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else
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{
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__real__ Res = sinh (two_R) / denom;
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__imag__ Res = sin (two_I) / denom;
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}
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return Res;
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}
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