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# Manual Reference Pages  -  MATH::GSL::SYS (3)

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### NAME

Math::GSL::Sys - Misc Math Functions

### SYNOPSIS



use Math::GSL::Sys qw/:all/;



### DESCRIPTION

This module contains various useful math functions that are not usually provided by standard libraries.
o gsl_log1p($x) This function computes the value of \log(1+$x) in a way that is accurate for small $x. It provides an alternative to the BSD math function log1p(x). o gsl_expm1($x)

This function computes the value of \exp($x)-1 in a way that is accurate for small$x. It provides an alternative to the BSD math function expm1(x).

o gsl_hypot($x,$y)

This function computes the value of \sqrt{$x^2 +$y^2} in a way that avoids overflow. It provides an alternative to the BSD math function hypot($x,$y).

o gsl_hypot3($x,$y, $z) This function computes the value of \sqrt{$x^2 + $y^2 +$z^2} in a way that avoids overflow.

o gsl_acosh($x) This function computes the value of \arccosh($x). It provides an alternative to the standard math function acosh($x). o gsl_asinh($x)

This function computes the value of \arcsinh($x). It provides an alternative to the standard math function asinh($x).

o gsl_atanh($x) This function computes the value of \arctanh($x). It provides an alternative to the standard math function atanh($x). o gsl_isnan($x)

This function returns 1 if $x is not-a-number. o gsl_isinf($x)

This function returns +1 if $x is positive infinity, -1 if$x is negative infinity and 0 otherwise.

o gsl_finite($x) This function returns 1 if$x is a real number, and 0 if it is infinite or not-a-number.

o gsl_posinf
o gsl_neginf
o gsl_fdiv
o gsl_coerce_double
o gsl_coerce_float
o gsl_coerce_long_double
o gsl_ldexp($x,$e)

This function computes the value of $x * 2**$e. It provides an alternative to the standard math function ldexp($x,$e).

o gsl_frexp($x) This function splits the number$x into its normalized fraction f and exponent e, such that $x = f * 2^e and 0.5 <= f < 1. The function returns f and then the exponent in e. If$x is zero, both f and e are set to zero. This function provides an alternative to the standard math function frexp(x, e).

o gsl_fcmp($x,$y, $epsilon) This function determines whether$x and $y are approximately equal to a relative accuracy$epsilon. The relative accuracy is measured using an interval of size 2 \delta, where \delta = 2^k \epsilon and k is the maximum base-2 exponent of $x and$y as computed by the function frexp. If $x and$y lie within this interval, they are considered approximately equal and the function returns 0. Otherwise if $x <$y, the function returns -1, or if $x >$y, the function returns +1. Note that $x and$y are compared to relative accuracy, so this function is not suitable for testing whether a value is approximately zero. The implementation is based on the package fcmp by T.C. Belding.

For more informations on the functions, we refer you to the GSL offcial documentation: <http://www.gnu.org/software/gsl/manual/html_node/>

### AUTHORS

Jonathan Duke Leto <jonathan@leto.net> and Thierry Moisan <thierry.moisan@gmail.com>