EXP(S) UNIX System V EXP(S)
Name
exp, log, log10, pow, sqrt - exponential, logarithm, power,
square root functions
Syntax
#include <math.h>
double exp (x)
double x;
double log (x)
double x;
double log10 (x)
double x;
double pow (x, y)
double x, y;
double sqrt (x)
double x;
Description
The exp function 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.
See Also
hypot(S), matherr(S), sinh(S)
Diagnostics
The exp function returns HUGE when the correct value would
overflow, or 0 when the correct value would underflow, and
sets errno to ERANGE.
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.
These error-handling procedures may be changed with the
function matherr(S).
Standards Conformance
exp is conformant with:
AT&T SVID Issue 2, Select Code 307-127;
The X/Open Portability Guide II of January 1987;
IEEE POSIX Std 1003.1-1988 with C Standard Language-
Dependent System Support;
and NIST FIPS 151-1.
log, log10, pow and sqrt are conformant with:
AT&T SVID Issue 2, Select Code 307-127;
The X/Open Portability Guide II of January 1987;
ANSI X3.159-198X C Language Draft Standard, May 13,
1988;
IEEE POSIX Std 1003.1-1988 with C Standard Language-
Dependent System Support;
and NIST FIPS 151-1.
(printed 6/20/89)