x86 Instruction Set Reference

SQRTSD - Compute Square Root of Scalar Double-Precision Floating-Point Value

Opcode Mnemonic Description
F2 0F 51 /r SQRTSD xmm1, xmm2/m64 Compute the square root of the low double-precision floating-point value in xmm2/m64 and store the results in xmm1.
Description

Computes the square root of the low double-precision floating-point value in the source operand (second operand) and stores the double-precision floating-point result in the destination operand. The source operand can be an XMM register or a 64-bit memory location. The destination operand is an XMM register. The high quadword of the destination operand remains unchanged. See Figure 11-4 in the IA-32 Intel Architecture Software Developer's Manual, Volume 1 for an illustration of a scalar double-precision floating-point operation.
Operation 
Destination[0..63] = SquareRoot(Source[0..63]);
//Destination[64..127] remains unchanged
Instruction Latency Throughput Execution Unit
CPUID0F3n/0F2n/069n0F3n/0F2n/069n0F2n
SQRTSD xmm, xmm39/38/5839/38/57FP_DIV