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47 lines
798 B
Go
47 lines
798 B
Go
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// compile
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// Copyright 2016 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// This tickles (a version of) the PPC64 back end to
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// emit a BVS instruction.
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package foo
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type Flag int
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const (
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Identity Flag = iota - 2 // H is the identity matrix; no rotation is needed.
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Rescaling // H specifies rescaling.
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)
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type DrotmParams struct {
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Flag
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}
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func Drotmg(d1, d2, x1, y1 float64) (p DrotmParams, rd1, rd2, rx1 float64) {
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const (
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gam = 4.0
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gamsq = 16.0
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rgamsq = 5e-8
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)
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if d1 < 0 {
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p.Flag = Rescaling
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return
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}
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for rd1 <= rgamsq || rd1 >= gamsq {
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if rd1 <= rgamsq {
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rd1 *= gam * gam
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rx1 /= gam
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} else {
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rd1 /= gam * gam
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rx1 *= gam
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}
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}
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return
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}
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