input value
reciprocal square root of x
var v = rsqrt( 4.0 );
// returns 0.5
var v = rsqrt( 100.0 );
// returns 0.1
var v = rsqrt( 0.0 );
// returns Infinity
var v = rsqrt( Infinity );
// returns 0.0
var v = rsqrt( -4.0 );
// returns NaN
var v = rsqrt( NaN );
// returns NaN
Computes the reciprocal square root of a double-precision floating-point number.
Notes
x < 0
, the reciprocal square root is not defined.