83 lines
1.4 KiB
C
83 lines
1.4 KiB
C
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/*
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cacos.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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#if 0
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/* cacos (Z) = -I * clog(Z + I * csqrt(1 - Z * Z)) */
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double complex cacos (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 = acos (x);
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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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double complex ZZ;
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/* Z * Z = ((x - y) * (x + y)) + (2.0 * x * y) * I */
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/* caculate 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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Res = csqrt(ZZ);
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/* calculate ZZ + I * sqrt (ZZ) */
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__real__ ZZ = x - __imag__ Res;
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__imag__ ZZ = y + __real__ Res;
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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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#else
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/* cacos ( Z ) = pi/2 - casin ( Z ) */
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double complex cacos (double complex Z)
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{
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double complex Res = casin (Z);
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__real__ Res = M_PI_2 - __real__ Res;
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__imag__ Res = - __imag__ Res;
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return Res;
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}
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#endif
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#if 0
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#include <stdio.h>
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int main()
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{
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double z;
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double complex bar = 0.7 + 1.2 * I;
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double complex foo = cacos (bar);
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printf ("%.16e\t%.16e\n", __real__ foo, __imag__ foo);
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foo = cacos (bar);
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printf ("%.16e\t%.16e\n", __real__ foo, __imag__ foo);
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return 1;
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}
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#endif
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