NAME

exp, log, log10, pow, sqrt − exponential, logarithm, power, square root functions

SYNOPSIS

#include <math.h>

double exp (x) float fexp (x)
double x;‡float x;

double log (x) float flog (x)
double x;‡float x;

double log10 (x) float flog10 (x)
double x;‡float x;

double pow (x, y) float fpow
double x, y;‡float x,y;

double sqrt (x) float fsqrt (x)
double x;‡float x;

‡ see important note below

HP-UX COMPATIBILITY

Level: HP-UX/RUN ONLY

Origin: System V

DESCRIPTION

Exp returns ex. 

Log returns the natural logarithm of x. The value of x must be positive. 

Log10 returns the logarithm base ten of x. The value of x must be positive. 

Pow returns xy.  If x is zero, y must be positive.  If x is negative, y must be an integer. 

Sqrt returns the non-negative square root of x. The value of x may not be negative. 

IMPORTANT NOTE: The corresponding single-precision routines fexp, flog, flog10, fpow, and fsqrt expect true single-precision arguments, and therefore cannot be called from standard C.  They are provided for support of FORTRAN and Pascal. 

HARDWARE DEPENDENCIES

Series 200/500:
The algorithms used are those from HP 9000 BASIC.

DIAGNOSTICS

Exp sets errno to ERANGE and returns HUGE when the correct value would overflow, or 0 when the correct value would underflow. 

Log and log10 return −HUGE and set errno to EDOM when x is non-positive.  A message indicating DOMAIN error (or SING error when x is 0) is printed on the standard error output. 

Pow returns 0 and sets errno to EDOM when x is 0 and y is non-positive, or when x is negative and y is not an integer.  In these cases a message indicating DOMAIN error is printed on the standard error output.  When the correct value for pow would overflow or underflow, pow returns ±HUGE or 0 respectively, and sets errno to ERANGE. 

Sqrt returns 0 and sets errno to EDOM when x is negative.  A message indicating DOMAIN error is printed on the standard error output. 

Error handling is identical for both single- and double-precision routines, except for one consideration:  In any situation where the double-precision routine would return ±HUGE, the corresponding single-precision routine returns ±MAXFLOAT. 

These error-handling procedures may be changed with the function matherr(3M).

SEE ALSO

hypot(3M), matherr(3M), sinh(3M). 

Hewlett-Packard  —  last mod. May 11, 2021