casinf, casin, casinl

From cppreference.com
< c‎ | numeric‎ | complex
Defined in header <complex.h>
float complex       casinf( float complex z );
(1) (since C99)
double complex      casin( double complex z );
(2) (since C99)
long double complex casinl( long double complex z );
(3) (since C99)
Defined in header <tgmath.h>
#define asin( z )
(4) (since C99)
1-3) Computes the complex arc sine of z with branch cuts outside the interval [−1,+1] along the real axis.
4) Type-generic macro: If z has type long double complex, casinl is called. if z has type double complex, casin is called, if z has type float complex, casinf is called. If z is real or integer, then the macro invokes the corresponding real function (asinf, asin, asinl). If z is imaginary, then the macro invokes the corresponding real version of the function asinh, implementing the formula asin(iy) = i asinh(y), and the return type of the macro is imaginary.

Parameters

z - complex argument

Return value

If no errors occur, complex arc sine of z is returned, in the range of a strip unbounded along the imaginary axis and in the interval [−π/2; +π/2] along the real axis.

Errors and special cases are handled as if the operation is implemented by -I * casinh(I*z)

Notes

Inverse sine (or arc sine) is a multivalued function and requires a branch cut on the complex plane. The branch cut is conventionally placed at the line segments (-∞,-1) and (1,∞) of the real axis.

The mathematical definition of the principal value of arc sine is asin z = -iln(iz + 1-z2
)

For any z, asin(z) = acos(-z) -
π
2