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49 lines
1.1 KiB
Go
49 lines
1.1 KiB
Go
// Copyright ©2015 The gonum 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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package testlapack
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import (
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"math/rand"
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"testing"
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"github.com/gonum/floats"
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)
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type Dlasv2er interface {
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Dlasv2(f, g, h float64) (ssmin, ssmax, snr, csr, snl, csl float64)
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}
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func Dlasv2Test(t *testing.T, impl Dlasv2er) {
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rnd := rand.New(rand.NewSource(1))
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for i := 0; i < 100; i++ {
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f := rnd.NormFloat64()
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g := rnd.NormFloat64()
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h := rnd.NormFloat64()
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ssmin, ssmax, snr, csr, snl, csl := impl.Dlasv2(f, g, h)
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// tmp =
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// [ csl snl] [f g]
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// [-snl csl] [0 h]
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tmp11 := csl * f
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tmp12 := csl*g + snl*h
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tmp21 := -snl * f
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tmp22 := -snl*g + csl*h
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// lhs =
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// [tmp11 tmp12] [csr -snr]
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// [tmp21 tmp22] [snr csr]
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ans11 := tmp11*csr + tmp12*snr
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ans12 := tmp11*-snr + tmp12*csr
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ans21 := tmp21*csr + tmp22*snr
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ans22 := tmp21*-snr + tmp22*csr
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lhs := []float64{ans11, ans12, ans21, ans22}
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rhs := []float64{ssmax, 0, 0, ssmin}
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if !floats.EqualApprox(rhs, lhs, 1e-12) {
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t.Errorf("SVD mismatch. f = %v, g = %v, h = %v.\nLHS: %v\nRHS: %v", f, g, h, lhs, rhs)
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}
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}
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}
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