# _mm256_round_pd

Rounds off double-precision floating point values to nearest upper/lower integer depending on rounding mode. The corresponding Intel® AVX instruction isVROUNDPD.

## Syntax

extern __m256d _mm256_round_pd(__m256d a, int iRoundMode);

## Arguments

a | float64 vector
iRoundMode | A hexadecimal value dependent on rounding mode: For rounding off to upper integer, the value is `0x0A` For rounding off to lower integer, the value is `0x09`

## Description

Rounds off the elements of a float64 vector a to the nearest upper/lower integer value. Two shortcuts, in the form of `#defines`, are used to achieve these two separate operations:

    #define _mm256_ceil_pd(a)   _mm256_round_pd((a), 0x0A)

    #define _mm256_floor_pd(a)  _mm256_round_pd((a), 0x09)

These `#defines` tell the preprocessor to replace all instances of _mm256_ceil_pd(a) with _mm256_round_pd((a), 0x0A) and all instances of _mm256_floor_pd(a) with _mm256_round_pd((a), 0x09).

For example, if you write the following:

    __m256 a, b;

    a = _mm256_ceil_pd(b);

the preprocessor will modify it to:

    a = _mm256_round_pd(b, 0x0a);

The Precision Floating Point Exception is signaled according to the (immediate operand) iRoundMode value.

## Returns

Result of the rounding off operation as a vector with double-precision floating point values.

Parent topic: Intrinsics for Miscellaneous Operations