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_mm_fnmadd_sd

Multiply-adds negated scalar double-precision floating-point values of three float64 vectors. The corresponding FMA instruction is
VFNMADD<XXX>SD
, where XXX could be 132, 213, or 231.

Syntax

extern __m128d _mm_fnmadd_sd(__m128d a, __m128d b, __m128d c);
Arguments
a
float64 vector used for the operation
b
float64 vector also used for the operation
c
float64 vector also used for the operation
Description
Performs a set of scalar SIMD negated multiply-add computation on scalar double-precision floating-point values in the low 64-bits of three source operands,
a
,
b
, and
c
. The float64 values in two operands,
a
and
b
, are multiplied and the negated infinite precision intermediate result obtained is added to the float64 value in the third operand,
c
. The final result is rounded to the nearest float64 value.
The compiler defaults to using the
VFNMADD213SD
instruction and uses the other forms
VFNMADD132SD
or
VFNMADD231SD
only if a low level optimization decides it as useful or necessary. For example, the compiler could change the default if it finds that another instruction form saves a register or eliminates a move.
Returns
Result of the negated multiply-add operation.