vrhypot_(3MVEC) Vector Math Library Functions vrhypot_(3MVEC)NAME
vrhypot_, vrhypotf_ - vector reciprocal hypotenuse functions
SYNOPSIS
cc [ flag... ] file... -lmvec [ library... ]
void vrhypot_(int *n, double * restrict x, int *stridex,
double * restrict y, int *stridey, double * restrict z,
int *stridez);
void vrhypotf_(int *n, float * restrict x, int *stridex,
float * restrict y, int *stridey, float * restrict z,
int *stridez);
DESCRIPTION
These functions evaluate the function rhypot(x, y), defined by rhy‐
pot(x, y) = 1 / hypot(x, y), for an entire vector of values at once.
The first parameter specifies the number of values to compute. Subse‐
quent 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, vrhypot_(n, x, sx, y, sy, z, sz) computes z[i * *sz] =
rhypot(x[i * *sx], y[i * *sy]) for each i = 0, 1, ..., *n - 1. The
vrhypotf_() function performs the same computation for single preci‐
sion data.
These functions are not guaranteed to deliver results that are identi‐
cal to the results of evaluating 1.0 / hypot(x, y) given the same argu‐
ments. 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 vector 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 convention differs from the
Level 1 BLAS, in which array parameters always refer to the lowest-
addressed element in memory even when negative increments are used.
These functions assume that the default round-to-nearest rounding
direction mode is in effect. On x86, these functions 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 undefined.
These functions handle special cases and exceptions in the spirit of
IEEE 754. In particular,
o if x or y is ±Inf, rhypot(x, y) is +0, even if the other of
x or y is NaN,
o if x or y is NaN and neither is infinite, rhypot(x, y) is
NaN
o if x and y are both zero, rhypot(x, y) is +0, and a divi‐
sion-by-zero exception is raised.
An application wanting to check for exceptions should call feclearex‐
cept(FE_ALL_EXCEPT) before calling these functions. On return, if
fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is
non-zero, an exception has been raised. The application can then exam‐
ine the result or argument vectors for exceptional values. Some vector
functions can raise the inexact exception even if all elements of the
argument array are such that the numerical results are exact.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Committed │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │MT-Safe │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOhypot(3M), feclearexcept(3M), fetestexcept(3M), attributes(5)SunOS 5.10 14 Dec 2007 vrhypot_(3MVEC)
