1vatan2_(3MVEC)           Vector Math Library Functions          vatan2_(3MVEC)
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NAME

6       vatan2_, vatan2f_ - vector atan2 functions
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SYNOPSIS

9       cc [ flag... ] file... -lmvec [ library... ]
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11       void vatan2_(int *n, double * restrict y, int *stridey,
12            double * restrict x, int *stridex, double * restrict z,
13            int *stridez);
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16       void vatan2f_(int *n, float * restrict y, int *stridey,
17            float * restrict x, int *stridex, float * restrict z,
18            int *stridez);
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DESCRIPTION

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.
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29       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.
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35       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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USAGE

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.
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53       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.
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60       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.
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65       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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ATTRIBUTES

74       See attributes(5) for descriptions of the following attributes:
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79       ┌─────────────────────────────┬─────────────────────────────┐
80       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
81       ├─────────────────────────────┼─────────────────────────────┤
82       │Interface Stability          │Committed                    │
83       ├─────────────────────────────┼─────────────────────────────┤
84       │MT-Level                     │MT-Safe                      │
85       └─────────────────────────────┴─────────────────────────────┘
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SEE ALSO

88       atan2(3M), feclearexcept(3M), fetestexcept(3M), attributes(5)
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92SunOS 5.11                        14 Dec 2007                   vatan2_(3MVEC)
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