Vector Math Library Functions                        vpow(3MVEC)



NAME
     vpow, vpowf - vector power functions

SYNOPSIS
     cc [ flag... ] file... -lmvec [ library... ]

     void vpow(int *n, double * restrict x, int *stridex,
          double * restrict y, int *stridey, double * restrict z,
          int *stridez);


     void vpowf(int *n, float * restrict x, int *stridex,
          float * restrict y, int *stridey, float * restrict z,
          int *stridez);


DESCRIPTION
     These functions evaluate  the  function  pow(x,  y)  for  an
     entire  vector of values at once. The first parameter speci-
     fies the number of values to compute. Subsequent  parameters
     specify  the  argument  and  result  vectors. Each vector is
     described by a pointer to the first element  and  a  stride,
     which is the increment between successive elements.


     Specifically, vpow(n, x, sx, y, sy, z, sz) computes  z[i  *
     *sz]  =  pow(x[i * *sx], y[i * *sy]) for each i = 0, 1, ...,
     *n - 1. The vpowf() function performs the same  computation
     for single precision data.


     These functions are not guaranteed to deliver  results  that
     are  identical to the results of the pow(3M) functions given
     the same arguments. Non-exceptional  results,  however,  are
     accurate to within a unit in the last place.

USAGE
     The element count *n must be greater than zero. The  strides
     for   the  argument  and  result  arrays  can  be  arbitrary
     integers, but the arrays themselves must not be the same  or
     overlap.  A zero stride effectively collapses an entire vec-
     tor into a single element. A negative stride causes a vector
     to be accessed in descending memory order, but note that the
     corresponding pointer must still point to the first  element
     of  the  vector  to be used; if the stride is negative, this
     will be the highest-addressed element in memory.  This  con-
     vention differs from the Level 1 BLAS, in which array param-
     eters always refer to the lowest-addressed element in memory
     even when negative increments are used.






SunOS 5.11          Last change: 16 Jan 2009                    1






Vector Math Library Functions                        vpow(3MVEC)



     These functions assume  that  the  default  round-to-nearest
     rounding  direction  mode  is in effect. On x86, these func-
     tions also assume that the default round-to-64-bit  rounding
     precision  mode is in effect. The result of calling a vector
     function with a non-default rounding mode in effect is unde-
     fined.


     The results of these functions for special cases and  excep-
     tions  match that of the pow() functions when the latter are
     used in a program compiled with the cc compiler driver (that
     is,     not    SUSv3-conforming)    and    the    expression
     (matherrhandling & MATHEREXCEPT) is non-zero. These func-
     tions do not set errno. See pow(3M) for the results for spe-
     cial cases.


     An application wanting to check for exceptions  should  call
     feclearexcept(FEALEXCEPT) before calling these functions.
     On  return,  if  fetestexcept(FEINVALID    FEDIVBYZERO  
     FEOVERFLOW    FEUNDERFLOW)  is non-zero, an exception has
     been raised. The application can then examine the result  or
     argument  vectors  for exceptional values. Some vector func-
     tions can raise the inexact exception even if  all  elements
     of  the  argument  array are such that the numerical results
     are exact.

ATRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:



     
           ATRIBUTE TYPE               ATRIBUTE VALUE       
    
     Interface Stability          Committed                   
    
     MT-Level                     MT-Safe                     
    


SEE ALSO
     pow(3M), feclearexcept(3M), fetestexcept(3M), attributes(5)











SunOS 5.11          Last change: 16 Jan 2009                    2