1vatan2_(3MVEC) Vector Math Library Functions vatan2_(3MVEC)
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6 vatan2_, vatan2f_ - vector atan2 functions
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9 cc [ flag... ] file... -lmvec [ library... ]
10 void vatan2_(int *n, double * restrict y, int *stridey,
12 double * restrict x, int *stridex, double * restrict z,
13 int *stridez);
14 void vatan2f_(int *n, float * restrict y, int *stridey,
17 float * restrict x, int *stridex, float * restrict z,
18 int *stridez);
19
22 These functions evaluate the function atan2(y, x) for an entire vector
23 of values at once. The first parameter specifies the number of values
24 to compute. Subsequent parameters specify the argument and result vec‐
25 tors. Each vector is described by a pointer to the first element and a
26 stride, which is the increment between successive elements.
27 Specifically, vatan2_(n, y, sy, x, sx, z, sz) computes z[i * *sz] =
30 atan2(y[i * *sy], x[i * *sx]) for each i = 0, 1, ..., *n - 1. The
31 vatan2f_() function performs the same computation for single precision
32 data.
33 These functions are not guaranteed to deliver results that are identi‐
36 cal to the results of the atan2(3M) functions given the same arguments.
37 Non-exceptional results, however, are accurate to within a unit in the
38 last place.
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41 The element count *n must be greater than zero. The strides for the
42 argument and result arrays can be arbitrary integers, but the arrays
43 themselves must not be the same or overlap. A zero stride effectively
44 collapses an entire vector into a single element. A negative stride
45 causes a vector to be accessed in descending memory order, but note
46 that the corresponding pointer must still point to the first element of
47 the vector to be used; if the stride is negative, this will be the
48 highest-addressed element in memory. This convention differs from the
49 Level 1 BLAS, in which array parameters always refer to the lowest-
50 addressed element in memory even when negative increments are used.
51 These functions assume that the default round-to-nearest rounding
54 direction mode is in effect. On x86, these functions also assume that
55 the default round-to-64-bit rounding precision mode is in effect. The
56 result of calling a vector function with a non-default rounding mode in
57 effect is undefined.
58 These functions handle special cases and exceptions in the same way as
61 the atan2() functions when c99 MATHERREXCEPT conventions are in effect.
62 See atan2(3M) for the results for special cases.
63 An application wanting to check for exceptions should call feclearex‐
66 cept(FE_ALL_EXCEPT) before calling these functions. On return, if
67 fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is
68 non-zero, an exception has been raised. The application can then exam‐
69 ine the result or argument vectors for exceptional values. Some vector
70 functions can raise the inexact exception even if all elements of the
71 argument array are such that the numerical results are exact.
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74 See attributes(5) for descriptions of the following attributes:
75 ┌─────────────────────────────┬─────────────────────────────┐
80 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
81 ├─────────────────────────────┼─────────────────────────────┤
82 │Interface Stability │Committed │
83 ├─────────────────────────────┼─────────────────────────────┤
84 │MT-Level │MT-Safe │
85 └─────────────────────────────┴─────────────────────────────┘
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88 atan2(3M), feclearexcept(3M), fetestexcept(3M), attributes(5)
89SunOS 5.11 14 Dec 2007 vatan2_(3MVEC)