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3-384 Vol. 2A FSQRT—Square Root
INSTRUCTION SET REFERENCE, A-M
FSQRT—Square Root
Description
Computes the square root of the source value in the ST(0) register and stores the
result in ST(0).
The following table shows the results obtained when taking the square root of various
classes of numbers, assuming that neither overflow nor underflow occurs.
This instruction’s operation is the same in non-64-bit modes and 64-bit mode.
Operation
ST(0) ← SquareRoot(ST(0));
FPU Flags Affected
C1 Set to 0 if stack underflow occurred.
Set if result was rounded up; cleared otherwise.
C0, C2, C3 Undefined.
Floating-Point Exceptions
#IS Stack underflow occurred.
#IA Source operand is an SNaN value or unsupported format.
Opcode Instruction 64-Bit
Mode
Compat/
Leg Mode
Description
D9 FA FSQRT Valid Valid Computes square root of ST(0) and stores
the result in ST(0).
Table 3-42. FSQRT Results
SRC (ST(0)) DEST (ST(0))
−∞ *
−
F *
−0 −0
+0 +0
+F +F
+
∞ +∞
NaN
NaN
NOTES:
F Means finite floating-point value.
* Indicates floating-point invalid-arithmetic-operand (#IA) exception.