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Diffstat (limited to 'src/runtime/complex.go')
-rw-r--r-- | src/runtime/complex.go | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/src/runtime/complex.go b/src/runtime/complex.go new file mode 100644 index 000000000..ec50f8947 --- /dev/null +++ b/src/runtime/complex.go @@ -0,0 +1,52 @@ +// Copyright 2010 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 runtime + +func complex128div(n complex128, d complex128) complex128 { + // Special cases as in C99. + ninf := real(n) == posinf || real(n) == neginf || + imag(n) == posinf || imag(n) == neginf + dinf := real(d) == posinf || real(d) == neginf || + imag(d) == posinf || imag(d) == neginf + + nnan := !ninf && (real(n) != real(n) || imag(n) != imag(n)) + dnan := !dinf && (real(d) != real(d) || imag(d) != imag(d)) + + switch { + case nnan || dnan: + return complex(nan, nan) + case ninf && !dinf: + return complex(posinf, posinf) + case !ninf && dinf: + return complex(0, 0) + case real(d) == 0 && imag(d) == 0: + if real(n) == 0 && imag(n) == 0 { + return complex(nan, nan) + } else { + return complex(posinf, posinf) + } + default: + // Standard complex arithmetic, factored to avoid unnecessary overflow. + a := real(d) + if a < 0 { + a = -a + } + b := imag(d) + if b < 0 { + b = -b + } + if a <= b { + ratio := real(d) / imag(d) + denom := real(d)*ratio + imag(d) + return complex((real(n)*ratio+imag(n))/denom, + (imag(n)*ratio-real(n))/denom) + } else { + ratio := imag(d) / real(d) + denom := imag(d)*ratio + real(d) + return complex((imag(n)*ratio+real(n))/denom, + (imag(n)-real(n)*ratio)/denom) + } + } +} |