sqrt

Square root.

SYNOPSIS:

double x, y, sqrt();
y = sqrt(x);

DESCRIPTION:
Returns the square root of x.
Range reduction involves isolating the power of two of the argument and using a polynomial approximation to obtain a rough value for the square root. Then Heron's iteration is used three times to converge to an accurate value.

ACCURACY:
Relative error:
arithmetic domain # trials peak rms
DEC 0, 10 60000 2.1e-17 7.9e-18
IEEE 0,1.7e308 30000 1.7e-16 6.3e-17


ERROR MESSAGES:

message condition value returned
domain x < 0 0.0