ccosf, ccos, ccosl

C

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Type support

Program utilities

Variadic function support

Error handling

Dynamic memory management

Date and time utilities

Strings library

Algorithms

Numerics

Input/output support

Localization support

Atomic operations (C11)

Thread support (C11)

Technical Specifications

Numerics

Common mathematical functions

Floating-point environment

Complex number arithmetics

Random number generation

Type-generic math

Complex number arithmetic

Types and the imaginary constant
complex _Complex_I CMPLX	imaginary _Imaginary_I I
Manipulation
cimag creal carg	cabs conj cproj
Power and exponential functions
cexp clog	cpow csqrt
Trigonometric functions
ccos csin ctan	cacos casin catan
Hyperbolic functions
ccosh csinh ctanh	cacosh casinh catanh

Defined in header <complex.h>
float complex ccosf( float complex z );	(1)	(since C99)
double complex ccos( double complex z );	(2)	(since C99)
long double complex ccosl( long double complex z );	(3)	(since C99)
Defined in header <tgmath.h>
#define cos( z )	(4)	(since C99)

1-3) Computes the complex cosine of z.

4) Type-generic macro: If z has type long double complex, ccosl is called. if z has type double complex, ccos is called, if z has type float complex, ccosf is called. If z is real or integer, then the macro invokes the corresponding real function (cosf, cos, cosl). If z is imaginary, then the macro invokes the corresponding real version of the function cosh, implementing the formula cos(iy) = cosh(y), and the return type is real.

Parameters

z

-

complex argument

Return value

If no errors occur, the complex cosine of z is returned.

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

Notes

The cosine is an entire function on the complex plane, and has no branch cuts.

Mathematical definition of the cosine is cos z =

eiz +e-iz

2

Example

Run this code

#include <stdio.h>
#include <math.h>
#include <complex.h>

int main(void)
{
    double complex z = ccos(1);  // behaves like real cosine along the real line
    printf("cos(1+0i) =%f%+fi ( cos(1)=%f)\n", creal(z), cimag(z), cos(1));

    double complex z2 = ccos(I); // behaves like real cosh along the imaginary line
    printf("cos(0+1i) =%f%+fi (cosh(1)=%f)\n", creal(z2), cimag(z2), cosh(1));
}

Output:

cos(1+0i) = 0.540302-0.000000i ( cos(1)=0.540302)
cos(0+1i) = 1.543081-0.000000i (cosh(1)=1.543081)

References

• C11 standard (ISO/IEC 9899:2011):

• 7.3.5.4 The ccos functions (p: 191)

• 7.25 Type-generic math <tgmath.h> (p: 373-375)

• G.7 Type-generic math <tgmath.h> (p: 545)

• C99 standard (ISO/IEC 9899:1999):

• 7.3.5.4 The ccos functions (p: 173)

• 7.22 Type-generic math <tgmath.h> (p: 335-337)

• G.7 Type-generic math <tgmath.h> (p: 480)

See also

csincsinfcsinl (C99)(C99)(C99)	computes the complex sine (function)
ctanctanfctanl (C99)(C99)(C99)	computes the complex tangent (function)
cacoscacosfcacosl (C99)(C99)(C99)	computes the complex arc cosine (function)
coscosfcosl (C99)(C99)	computes cosine (cos(x)) (function)