| // 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 |
| #include "runtime.h" |
| |
| func complex128div(n Complex128, d Complex128) (q Complex128) { |
| int32 ninf, dinf, nnan, dnan; |
| float64 a, b, ratio, denom; |
| |
| // Special cases as in C99. |
| ninf = n.real == runtime·posinf || n.real == runtime·neginf || |
| n.imag == runtime·posinf || n.imag == runtime·neginf; |
| dinf = d.real == runtime·posinf || d.real == runtime·neginf || |
| d.imag == runtime·posinf || d.imag == runtime·neginf; |
| |
| nnan = !ninf && (ISNAN(n.real) || ISNAN(n.imag)); |
| dnan = !dinf && (ISNAN(d.real) || ISNAN(d.imag)); |
| |
| if(nnan || dnan) { |
| q.real = runtime·nan; |
| q.imag = runtime·nan; |
| } else if(ninf && !dinf) { |
| q.real = runtime·posinf; |
| q.imag = runtime·posinf; |
| } else if(!ninf && dinf) { |
| q.real = 0; |
| q.imag = 0; |
| } else if(d.real == 0 && d.imag == 0) { |
| if(n.real == 0 && n.imag == 0) { |
| q.real = runtime·nan; |
| q.imag = runtime·nan; |
| } else { |
| q.real = runtime·posinf; |
| q.imag = runtime·posinf; |
| } |
| } else { |
| // Standard complex arithmetic, factored to avoid unnecessary overflow. |
| a = d.real; |
| if(a < 0) |
| a = -a; |
| b = d.imag; |
| if(b < 0) |
| b = -b; |
| if(a <= b) { |
| ratio = d.real/d.imag; |
| denom = d.real*ratio + d.imag; |
| q.real = (n.real*ratio + n.imag) / denom; |
| q.imag = (n.imag*ratio - n.real) / denom; |
| } else { |
| ratio = d.imag/d.real; |
| denom = d.imag*ratio + d.real; |
| q.real = (n.imag*ratio + n.real) / denom; |
| q.imag = (n.imag - n.real*ratio) / denom; |
| } |
| } |
| } |