exp(S)                         6 January 1993                         exp(S)


 Name

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

 Syntax


    cc  . . .  -lm


    #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 e^x.

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

    The log10 function returns the logarithm base ten of x.  The value of x
    must be positive.

    The pow function returns x^y.  If x is zero, y must be positive.  If x is
    negative, y must be an integer.

    The sqrt function returns the non-negative square root of x.  The value
    of x cannot 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.

    The log and log10 functions 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.

    Ihe pow function 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.

    The 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.

 Standards conformance

    exp is conformant with:
    AT&T SVID Issue 2;
    X/Open Portability Guide, Issue 3, 1989;
    IEEE POSIX Std 1003.1-1990 System Application Program Interface (API) [C
    Language] (ISO/IEC 9945-1); and NIST FIPS 151-1.

    log, log10, pow and sqrt are conformant with:
    AT&T SVID Issue 2;
    X/Open Portability Guide, Issue 3, 1989;
    ANSI X3.159-1989 Programming Language -- C;
    IEEE POSIX Std 1003.1-1990 System Application Program Interface (API) [C
    Language] (ISO/IEC 9945-1);
    and NIST FIPS 151-1.