1vsqrt_(3MVEC) Vector Math Library Functions vsqrt_(3MVEC)
2
6 vsqrt_, vsqrtf_ - vector square root functions
7
9 cc [ flag... ] file... -lmvec [ library... ]
10 void vsqrt_(int *n, double * restrict x, int *stridex,
12 double * restrict y, int *stridey);
13 void vsqrtf_(int *n, float * restrict x, int *stridex,
16 float * restrict y, int *stridey);
17
20 These functions evaluate the function sqrt(x) for an entire vector of
21 values at once. The first parameter specifies the number of values to
22 compute. Subsequent parameters specify the argument and result vectors.
23 Each vector is described by a pointer to the first element and a
24 stride, which is the increment between successive elements.
25 Specifically, vsqrt_(n, x, sx, y, sy) computes y[i * *sy] = sqrt(x[i *
28 *sx]) for each i = 0, 1, ..., *n - 1. The vsqrtf_() function performs
29 the same computation for single precision data.
30 Unlike their scalar counterparts, these functions do not always deliver
33 correctly rounded results. However, the error in each non-exceptional
34 result is less than one unit in the last place.
35
37 The element count *n must be greater than zero. The strides for the
38 argument and result arrays can be arbitrary integers, but the arrays
39 themselves must not be the same or overlap. A zero stride effectively
40 collapses an entire vector into a single element. A negative stride
41 causes a vector to be accessed in descending memory order, but note
42 that the corresponding pointer must still point to the first element of
43 the vector to be used; if the stride is negative, this will be the
44 highest-addressed element in memory. This convention differs from the
45 Level 1 BLAS, in which array parameters always refer to the lowest-
46 addressed element in memory even when negative increments are used.
47 These functions assume that the default round-to-nearest rounding
50 direction mode is in effect. On x86, these functions also assume that
51 the default round-to-64-bit rounding precision mode is in effect. The
52 result of calling a vector function with a non-default rounding mode in
53 effect is undefined.
54 These functions handle special cases and exceptions in the same way
57 as the sqrt() functions when c99 MATHERREXCEPT conventions are in
58 effect. See sqrt(3M) for the results for special cases.
59 An application wanting to check for exceptions should call feclearex‐
62 cept(FE_ALL_EXCEPT) before calling these functions. On return, if
63 fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is
64 non-zero, an exception has been raised. The application can then exam‐
65 ine the result or argument vectors for exceptional values. Some vector
66 functions can raise the inexact exception even if all elements of the
67 argument array are such that the numerical results are exact.
68
70 See attributes(5) for descriptions of the following attributes:
71 ┌─────────────────────────────┬─────────────────────────────┐
76 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
77 ├─────────────────────────────┼─────────────────────────────┤
78 │Interface Stability │Committed │
79 ├─────────────────────────────┼─────────────────────────────┤
80 │MT-Level │MT-Safe │
81 └─────────────────────────────┴─────────────────────────────┘
82
84 sqrt(3M), feclearexcept(3M), fetestexcept(3M), attributes(5)
85SunOS 5.11 14 Dec 2007 vsqrt_(3MVEC)