# _mm_i64gather_pd, _mm256_i64gather_pd

Gathers 2/4 packed double-precision floating point values from memory referenced by the given base address, qword indices, and scale. The corresponding Intel® AVX2 instruction is `VGATHERQPD`.

## Syntax

extern __m128d _mm_i64gather_pd(double const * base, __m128i vindex, const int scale);

extern __m256d _mm256_mask_i64gather_pd(double const * base, __m128i vindex, const int scale);

## Arguments

base | the base address used to reference the loaded FP elements.
vindex | the vector of qword indices used to reference the loaded FP elements.
scale | The compilation time literal constant, which is used as the vector indices scale to address the loaded elements. Possible values are one of the following: 1, 2, 4, 8.

## Description

The intrinsics load 2/4 packed double-precision floating-point values from memory using qword indices and updates the destination operand.

Below is the pseudo-code for the intrinsics:

`_mm_i64gather_pd()`:

    result[63:0] = mem[base+vindex[63:0]*scale];
    result[127:64] = mem[base+vindex[127:64]*scale];

`_mm256_i64gather_pd()`:

    result[63:0] = mem[base+vindex[63:0]*scale];
    result[127:64] = mem[base+vindex[127:64]*scale];
    result[191:128] = mem[base+vindex[191:128]*scale];
    result[255:192] = mem[base+vindex[255:192]*scale];

## Returns

A 128/256-bit vector with unconditionally gathered double-precision FP values.

Parent topic: Intrinsics for GATHER Operations