catanhf, catanh, catanhl

 

C

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Technical Specifications

Symbol index

 

Numerics

Common mathematical functions

Floating-point environment(C99)

Pseudo-random number generation

Complex number arithmetic(C99)

Type-generic math(C99)

Bit manipulation(C23)

Checked integer arithmetic(C23)

 

Complex number arithmetic

Types and the imaginary constant
complex (C99) _Complex_I (C99)     CMPLX (C11)	imaginary (C99) _Imaginary_I (C99) I (C99)
Manipulation
cimag (C99) creal (C99) carg (C99)	cabs (C99) conj (C99) cproj (C99)
Power and exponential functions
cexp (C99) clog (C99)	cpow (C99) csqrt (C99)
Trigonometric functions
ccos (C99) csin (C99) ctan (C99)	cacos (C99) casin (C99) catan (C99)
Hyperbolic functions
ccosh (C99) csinh (C99) ctanh (C99)	cacosh (C99) casinh (C99) catanh (C99)

 

Defined in header <complex.h>
floatcomplex       catanhf(floatcomplex z );	(1)	(since C99)
doublecomplex      catanh(doublecomplex z );	(2)	(since C99)
longdoublecomplex catanhl(longdoublecomplex z );	(3)	(since C99)
Defined in header <tgmath.h>
#define atanh( z )	(4)	(since C99)

1-3) Computes the complex arc hyperbolic tangent of z with branch cuts outside the interval [−1; +1] along the real axis.

4) Type-generic macro: If z has type longdoublecomplex, catanhl is called. if z has type doublecomplex, catanh is called, if z has type floatcomplex, catanhf is called. If z is real or integer, then the macro invokes the corresponding real function (atanhf, atanh, atanhl). If z is imaginary, then the macro invokes the corresponding real version of atan, implementing the formula atanh(iy) = i atan(y), and the return type is imaginary.

Parameters

z

-

complex argument

Return value

If no errors occur, the complex arc hyperbolic tangent of z is returned, in the range of a half-strip mathematically unbounded along the real axis and in the interval [−iπ/2; +iπ/2] along the imaginary axis.

Error handling and special values

Errors are reported consistent with math_errhandling

If the implementation supports IEEE floating-point arithmetic,

• catanh(conj(z))==conj(catanh(z))
• catanh(-z)==-catanh(z)
• If z is +0+0i, the result is +0+0i
• If z is +0+NaNi, the result is +0+NaNi
• If z is +1+0i, the result is +∞+0i and FE_DIVBYZERO is raised
• If z is x+∞i (for any finite positive x), the result is +0+iπ/2
• If z is x+NaNi (for any finite nonzero x), the result is NaN+NaNi and FE_INVALID may be raised
• If z is +∞+yi (for any finite positive y), the result is +0+iπ/2
• If z is +∞+∞i, the result is +0+iπ/2
• If z is +∞+NaNi, the result is +0+NaNi
• If z is NaN+yi (for any finite y), the result is NaN+NaNi and FE_INVALID may be raised
• If z is NaN+∞i, the result is ±0+iπ/2 (the sign of the real part is unspecified)
• If z is NaN+NaNi, the result is NaN+NaNi

Notes

Although the C standard names this function "complex arc hyperbolic tangent", the inverse functions of the hyperbolic functions are the area functions. Their argument is the area of a hyperbolic sector, not an arc. The correct name is "complex inverse hyperbolic tangent", and, less common, "complex area hyperbolic tangent".

Inverse hyperbolic tangent is a multivalued function and requires a branch cut on the complex plane. The branch cut is conventionally placed at the line segmentd (-∞,-1] and [+1,+∞) of the real axis.

The mathematical definition of the principal value of the inverse hyperbolic tangent is atanh z =

ln(1+z)-ln(z-1)

2

.

For any z, atanh(z) =

atan(iz)

i

Example

Run this code

#include <stdio.h>#include <complex.h>   int main(void){doublecomplex z = catanh(2);printf("catanh(+2+0i) = %f%+fi\n", creal(z), cimag(z));   doublecomplex z2 = catanh(conj(2));// or catanh(CMPLX(2, -0.0)) in C11printf("catanh(+2-0i) (the other side of the cut) = %f%+fi\n", creal(z2), cimag(z2));   // for any z, atanh(z) = atan(iz)/idoublecomplex z3 = catanh(1+2*I);printf("catanh(1+2i) = %f%+fi\n", creal(z3), cimag(z3));doublecomplex z4 =catan((1+2*I)*I)/I;printf("catan(i * (1+2i))/i = %f%+fi\n", creal(z4), cimag(z4));}

Output:

catanh(+2+0i) = 0.549306+1.570796i catanh(+2-0i) (the other side of the cut) = 0.549306-1.570796i catanh(1+2i) = 0.173287+1.178097i catan(i * (1+2i))/i = 0.173287+1.178097i

References

• C11 standard (ISO/IEC 9899:2011):

• 7.3.6.3 The catanh functions (p: 193)

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

• G.6.2.3 The catanh functions (p: 540-541)

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

• C99 standard (ISO/IEC 9899:1999):

• 7.3.6.3 The catanh functions (p: 175)

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

• G.6.2.3 The catanh functions (p: 475-476)

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

See also

casinhcasinhfcasinhl (C99)(C99)(C99)	computes the complex arc hyperbolic sine (function)
cacoshcacoshfcacoshl (C99)(C99)(C99)	computes the complex arc hyperbolic cosine (function)
ctanhctanhfctanhl (C99)(C99)(C99)	computes the complex hyperbolic tangent (function)
atanhatanhfatanhl (C99)(C99)(C99)	computes inverse hyperbolic tangent (\({\small\operatorname{artanh}{x} }\)artanh(x)) (function)
C++ documentation for atanh