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   6 .TH vatan2_ 3MVEC "14 Dec 2007" "SunOS 5.11" "Vector Math Library Functions"
   7 .SH NAME
   8 vatan2_, vatan2f_ \- vector atan2 functions
   9 .SH SYNOPSIS
  10 .LP
  11 .nf
  12 cc [ \fIflag\fR\&.\|.\|. ] \fIfile\fR\&.\|.\|. \fB-lmvec\fR [ \fIlibrary\fR\&.\|.\|. ]
  13 
  14 \fBvoid\fR \fBvatan2_\fR(\fBint *\fR\fIn\fR, \fBdouble * restrict\fR \fIy\fR, \fBint *\fR\fIstridey\fR,
  15      \fBdouble * restrict\fR \fIx\fR, \fBint *\fR\fIstridex\fR, \fBdouble * restrict\fR \fIz\fR,
  16      \fBint *\fR\fIstridez\fR);
  17 .fi
  18 
  19 .LP
  20 .nf
  21 \fBvoid\fR \fBvatan2f_\fR(\fBint *\fR\fIn\fR, \fBfloat * restrict\fR \fIy\fR, \fBint *\fR\fIstridey\fR,
  22      \fBfloat * restrict\fR \fIx\fR, \fBint *\fR\fIstridex\fR, \fBfloat * restrict\fR \fIz\fR,
  23      \fBint *\fR\fIstridez\fR);
  24 .fi
  25 
  26 .SH DESCRIPTION
  27 .sp
  28 .LP
  29 These functions evaluate the function \fBatan2\fR(\fIy\fR, \fIx\fR) for an
  30 entire vector of values at once. The first parameter specifies the number of
  31 values to compute. Subsequent parameters specify the argument and result
  32 vectors. Each vector is described by a pointer to the first element and a
  33 stride, which is the increment between successive elements.
  34 .sp
  35 .LP
  36 Specifically, \fBvatan2_\fR(\fIn,\fR \fIy\fR, \fIsy\fR, \fIx\fR, \fIsx\fR,
  37 \fIz\fR, \fIsz\fR) computes \fIz\fR[\fIi\fR * *\fIsz\fR] =
  38 \fBatan2\fR(\fIy\fR[\fIi\fR * *\fIsy\fR], \fIx\fR[\fIi\fR * *\fIsx\fR]) for
  39 each \fIi\fR = 0, 1, ..., *\fIn\fR - 1. The \fBvatan2f_()\fR  function performs
  40 the same computation for single precision data.
  41 .sp
  42 .LP
  43 These functions are not guaranteed to deliver results that are identical to the
  44 results of the \fBatan2\fR(3M) functions given the same arguments.
  45 Non-exceptional results, however, are accurate to within a unit in the last
  46 place.
  47 .SH USAGE
  48 .sp
  49 .LP
  50 The element count *\fIn\fR must be greater than zero. The strides for the
  51 argument and result arrays can be arbitrary integers, but the arrays themselves
  52 must not be the same or overlap. A zero stride effectively collapses an entire
  53 vector into a single element. A negative stride causes a vector to be accessed
  54 in descending memory order, but note that the corresponding pointer must still
  55 point to the first element of the vector to be used; if the stride is negative,
  56 this will be the highest-addressed element in memory. This convention differs
  57 from the Level 1 BLAS, in which array parameters always refer to the
  58 lowest-addressed element in memory even when negative increments are used.
  59 .sp
  60 .LP
  61 These functions assume that the default round-to-nearest rounding direction
  62 mode is in effect. On x86, these functions also assume that the default
  63 round-to-64-bit rounding precision mode is in effect. The result of calling a
  64 vector function with a non-default rounding mode in effect is undefined.
  65 .sp
  66 .LP
  67 These functions handle special cases and exceptions in the same way as the
  68 \fBatan2()\fR functions when \fBc99\fR \fBMATHERREXCEPT\fR conventions are in
  69 effect. See \fBatan2\fR(3M) for the results for special cases.
  70 .sp
  71 .LP
  72 An application wanting to check for exceptions should call
  73 \fBfeclearexcept\fR(\fBFE_ALL_EXCEPT\fR) before calling these functions. On
  74 return, if \fBfetestexcept\fR(\fBFE_INVALID\fR | \fBFE_DIVBYZERO\fR |
  75 \fBFE_OVERFLOW\fR | \fBFE_UNDERFLOW\fR) is non-zero, an exception has been
  76 raised. The application can then examine the result or argument vectors for
  77 exceptional values. Some vector functions can raise the inexact exception even
  78 if all elements of the argument array are such that the numerical results are
  79 exact.
  80 .SH ATTRIBUTES
  81 .sp
  82 .LP
  83 See \fBattributes\fR(5) for descriptions of the following attributes:
  84 .sp
  85 
  86 .sp
  87 .TS
  88 tab() box;
  89 cw(2.75i) |cw(2.75i) 
  90 lw(2.75i) |lw(2.75i) 
  91 .
  92 ATTRIBUTE TYPEATTRIBUTE VALUE
  93 _
  94 Interface StabilityCommitted
  95 _
  96 MT-LevelMT-Safe
  97 .TE
  98 
  99 .SH SEE ALSO
 100 .sp
 101 .LP
 102 \fBatan2\fR(3M), \fBfeclearexcept\fR(3M), \fBfetestexcept\fR(3M),
 103 \fBattributes\fR(5)