VATAN2_(3MVEC) Vector Math Library Functions VATAN2_(3MVEC)

## NAME

vatan2_, vatan2f_ - vector atan2 functions

## SYNOPSIS

cc [__flag__... ] __file__... **-lmvec **[ __library__... ]

**void vatan2_**(**int ***__n__, **double * restrict **__y__, **int ***__stridey__,

**double * restrict **__x__, **int ***__stridex__, **double * restrict **__z__,

**int ***__stridez__);

**void vatan2f_**(**int ***__n__, **float * restrict **__y__, **int ***__stridey__,

**float * restrict **__x__, **int ***__stridex__, **float * restrict **__z__,

**int ***__stridez__);

## DESCRIPTION

These functions evaluate the function**atan2**(__y__, __x__) for an entire vector of

values at once. The first parameter specifies the number of values to

compute. Subsequent 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,**vatan2_**(__n,__ __y__, __sy__, __x__, __sx__, __z__, __sz__) computes __z__[__i__ * *__sz__] =

**atan2**(__y__[__i__ * *__sy__], __x__[__i__ * *__sx__]) for each __i__ = 0, 1, ..., *__n__ - 1. The

**vatan2f_() **function performs the same computation for single precision

data.

These functions are not guaranteed to deliver results that are identical

to the results of the atan2(3M) functions given the same arguments. 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 same way as

the**atan2() **functions when **c99 MATHERREXCEPT **conventions are in effect.

See atan2(3M) for the results for special cases.

An application wanting to check for exceptions should call

**feclearexcept**(**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

examine 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 ALSO

atan2(3M), feclearexcept(3M), fetestexcept(3M), attributes(5)

SunOS 5.11 December 14, 2007 VATAN2_(3MVEC)

vatan2_, vatan2f_ - vector atan2 functions

cc [

These functions evaluate the function

values at once. The first parameter specifies the number of values to

compute. Subsequent 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,

data.

These functions are not guaranteed to deliver results that are identical

to the results of the atan2(3M) functions given the same arguments. Non-

exceptional results, however, are accurate to within a unit in the last

place.

The element count *

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 same way as

the

See atan2(3M) for the results for special cases.

An application wanting to check for exceptions should call

if

is non-zero, an exception has been raised. The application can then

examine 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.

See attributes(5) for descriptions of the following attributes:

+----------------------------+-----------------------------+

| ATTRIBUTE TYPE | ATTRIBUTE VALUE |

+----------------------------+-----------------------------+

|Interface Stability | Committed |

+----------------------------+-----------------------------+

|MT-Level | MT-Safe |

+----------------------------+-----------------------------+

atan2(3M), feclearexcept(3M), fetestexcept(3M), attributes(5)

SunOS 5.11 December 14, 2007 VATAN2_(3MVEC)