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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package math
/*
* sqrt returns the square root of its floating
* point argument. Newton's method.
*
* calls frexp
*/
// Sqrt returns the square root of x.
//
// Special cases are:
// Sqrt(+Inf) = +Inf
// Sqrt(0) = 0
// Sqrt(x < 0) = NaN
func Sqrt(x float64) float64 {
if IsInf(x, 1) {
return x;
}
if x <= 0 {
if x < 0 {
return NaN();
}
return 0;
}
y, exp := Frexp(x);
for y < 0.5 {
y = y*2;
exp = exp-1;
}
if exp&1 != 0 {
y = y*2;
exp = exp-1;
}
temp := 0.5 * (1+y);
for exp > 60 {
temp = temp * float64(1<<30);
exp = exp - 60;
}
for exp < -60 {
temp = temp / float64(1<<30);
exp = exp + 60;
}
if exp >= 0 {
exp = 1 << uint(exp/2);
temp = temp * float64(exp);
} else {
exp = 1 << uint(-exp/2);
temp = temp / float64(exp);
}
for i:=0; i<=4; i++ {
temp = 0.5*(temp + x/temp);
}
return temp;
}
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