ctanhf, ctanh, ctanhl

 

C

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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       ctanhf( float complex z );	(1)	(since C99)
double complex      ctanh( double complex z );	(2)	(since C99)
long double complex ctanhl( long double complex z );	(3)	(since C99)
Defined in header <tgmath.h>
#define tanh( z )	(4)	(since C99)

1-3) Computes the complex hyperbolic tangent of z.

4) Type-generic macro: If z has type long double complex, ctanhl is called. if z has type double complex, ctanh is called, if z has type float complex, ctanhf is called. If z is real or integer, then the macro invokes the corresponding real function (tanhf, tanh, tanhl). If z is imaginary, then the macro invokes the corresponding real version of the function tan, implementing the formula tanh(iy) = i tan(y), and the return type is imaginary.

Parameters

z

-

complex argument

Return value

If no errors occur, complex hyperbolic tangent of z is returned

Error handling and special values

Errors are reported consistent with math_errhandling

If the implementation supports IEEE floating-point arithmetic,

• ctanh(conj(z)) == conj(ctanh(z))
• ctanh(-z) == -ctanh(z)
• If z is +0+0i, the result is +0+0i
• If z is x+∞i (for any finite x), the result is NaN+NaNi and FE_INVALID is raised
• If z is x+NaN (for any finite x), the result is NaN+NaNi and FE_INVALID may be raised
• If z is +∞+yi (for any finite positive y), the result is 1+0i
• If z is +∞+∞i, the result is 1±0i (the sign of the imaginary part is unspecified)
• If z is +∞+NaNi, the result is 1±0i (the sign of the imaginary part is unspecified)
• If z is NaN+0i, the result is NaN+0i
• If z is NaN+yi (for any non-zero y), the result is NaN+NaNi and FE_INVALID may be raised
• If z is NaN+NaNi, the result is NaN+NaNi

Notes

Mathematical definition of hyperbolic tangent is cosh z =

ez -e-z

ez +e-z

Hyperbolic tangent is an analytical function on the complex plain and has no branch cuts. It is periodic with respect to the imaginary component, with period πi, and has poles of the first order along the imaginary line, at coordinates (0, π(1/2 + n)). However no common floating-point representation is able to represent π/2 exactly, thus there is no value of the argument for which a pole error occurs.

Example

Run this code

#include <stdio.h>
#include <math.h>
#include <complex.h>
 
int main(void)
{
    double complex z = ctanh(1);  // behaves like real tanh along the real line
    printf("tanh(1+0i) = %f%+fi (tanh(1)=%f)\n", creal(z), cimag(z), tanh(1));
 
    double complex z2 = ctanh(I); // behaves like tangent along the imaginary line
    printf("tanh(0+1i) = %f%+fi ( tan(1)=%f)\n", creal(z2), cimag(z2), tan(1));
}

Output:

tanh(1+0i) = 0.761594+0.000000i (tanh(1)=0.761594)
tanh(0+1i) = 0.000000+1.557408i ( tan(1)=1.557408)

References

• C11 standard (ISO/IEC 9899:2011):

• 7.3.6.6 The ctanh functions (p: 194)

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

• G.6.2.6 The ctanh functions (p: 542)

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

• C99 standard (ISO/IEC 9899:1999):

• 7.3.6.6 The ctanh functions (p: 176)

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

• G.6.2.6 The ctanh functions (p: 477)

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

See also

csinhcsinhfcsinhl (C99)(C99)(C99)	computes the complex hyperbolic sine (function)
ccoshccoshfccoshl (C99)(C99)(C99)	computes the complex hyperbolic cosine (function)
catanhcatanhfcatanhl (C99)(C99)(C99)	computes the complex arc hyperbolic tangent (function)
tanhtanhftanhl (C99)(C99)	computes hyperbolic tangent (function)
C++ documentation for tanh