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.
NOTES:
F Means finite floating-point value.
* Indicates floating-point invalid-arithmetic-operand (#IA) exception.
Operation
ST(0) ← SquareRoot(ST(0));
FPU Flags Affected
C1 Set to 0 if stack underflow occurred.
Indicates rounding direction if inexact-result exception (#P) is generated:
0 ← not roundup; 1 ← roundup.
C0, C2, C3 Undefined.
Opcode Instruction Description
D9 FA FSQRT Computes square root of ST(0) and stores the result in
ST(0)
SRC (ST(0)) DEST (ST(0))
−∞ *
−F *
−0 −0
+0 +0
+F +F
+∞ +∞
NaN NaN
INSTRUCTION SET REFERENCE
FSQRT—Square Root (Continued)
Floating-Point Exceptions
#IS Stack underflow occurred.
#IA Source operand is an SNaN value or unsupported format.
Source operand is a negative value (except for −0).
#D Source operand is a denormal value.
#P Value cannot be represented exactly in destination format.
Protected Mode Exceptions
#NM EM or TS in CR0 is set.
Real-Address Mode Exceptions
#NM EM or TS in CR0 is set.
Virtual-8086 Mode Exceptions
#NM EM or TS in CR0 is set.