github.com/akaros/go-akaros@v0.0.0-20181004170632-85005d477eab/src/runtime/complex.go (about)

     1  // Copyright 2010 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package runtime
     6  
     7  func complex128div(n complex128, d complex128) complex128 {
     8  	// Special cases as in C99.
     9  	ninf := real(n) == posinf || real(n) == neginf ||
    10  		imag(n) == posinf || imag(n) == neginf
    11  	dinf := real(d) == posinf || real(d) == neginf ||
    12  		imag(d) == posinf || imag(d) == neginf
    13  
    14  	nnan := !ninf && (real(n) != real(n) || imag(n) != imag(n))
    15  	dnan := !dinf && (real(d) != real(d) || imag(d) != imag(d))
    16  
    17  	switch {
    18  	case nnan || dnan:
    19  		return complex(nan, nan)
    20  	case ninf && !dinf:
    21  		return complex(posinf, posinf)
    22  	case !ninf && dinf:
    23  		return complex(0, 0)
    24  	case real(d) == 0 && imag(d) == 0:
    25  		if real(n) == 0 && imag(n) == 0 {
    26  			return complex(nan, nan)
    27  		} else {
    28  			return complex(posinf, posinf)
    29  		}
    30  	default:
    31  		// Standard complex arithmetic, factored to avoid unnecessary overflow.
    32  		a := real(d)
    33  		if a < 0 {
    34  			a = -a
    35  		}
    36  		b := imag(d)
    37  		if b < 0 {
    38  			b = -b
    39  		}
    40  		if a <= b {
    41  			ratio := real(d) / imag(d)
    42  			denom := real(d)*ratio + imag(d)
    43  			return complex((real(n)*ratio+imag(n))/denom,
    44  				(imag(n)*ratio-real(n))/denom)
    45  		} else {
    46  			ratio := imag(d) / real(d)
    47  			denom := imag(d)*ratio + real(d)
    48  			return complex((imag(n)*ratio+real(n))/denom,
    49  				(imag(n)-real(n)*ratio)/denom)
    50  		}
    51  	}
    52  }