49 lines
900 B
C
49 lines
900 B
C
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/*
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casin.c
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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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/* casin (Z ) = -I * clog(I * Z + csqrt (1.0 - Z * Z))) */
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double complex casin (double complex Z)
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{
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double complex Res;
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double x, y;
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x = __real__ Z;
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y = __imag__ Z;
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if (y == 0.0)
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{
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__real__ Res = asin (x);
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__imag__ Res = 0.0;
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}
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else /* -I * clog(I * Z + csqrt(1.0 - Z * Z))) */
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{
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double complex ZZ;
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/* Z * Z = ((x - y) * (x + y)) + (2.0 * x * y) * I */
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/* calculate 1 - Z * Z */
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__real__ ZZ = 1.0 - (x - y) * (x + y);
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__imag__ ZZ = -2.0 * x * y;
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ZZ = csqrt (ZZ);
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/* add I * Z to ZZ */
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__real__ ZZ -= y;
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__imag__ ZZ += x;
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ZZ = clog (ZZ);
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/* mult by -I */
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__real__ Res = __imag__ ZZ;
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__imag__ Res = - __real__ ZZ;
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}
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return (Res);
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}
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