EIGENVALUE_HELPER.h

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// This file is part of Wavelet Turbulence.
// 
// Wavelet Turbulence is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// 
// Wavelet Turbulence is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
// 
// You should have received a copy of the GNU General Public License
// along with Wavelet Turbulence.  If not, see <http://www.gnu.org/licenses/>.
// 
// Copyright 2008 Theodore Kim and Nils Thuerey
//
// Modified to not require TNT matrix library anymore. It was very slow
// when being run in parallel. Required TNT JAMA::Eigenvalue libraries were
// converted into independent functions.
//      - MiikaH
//
// Helper function, compute eigenvalues of 3x3 matrix

#ifndef EIGENVAL_HELPER_H
#define EIGENVAL_HELPER_H

//#include "tnt/jama_eig.h"

#include <algorithm>
#include <cmath>

using namespace std;

// eigenvalues of 3x3 non-symmetric matrix


struct sEigenvalue
{
    int n;
    int issymmetric;
    float d[3];         /* real part */
    float e[3];         /* img part */
    float V[3][3];      /* Eigenvectors */

    float H[3][3];
   

    float ort[3];

    float cdivr;
    float cdivi;
};

void Eigentred2(sEigenvalue& eval);

void Eigencdiv(sEigenvalue& eval, float xr, float xi, float yr, float yi);

void Eigentql2 (sEigenvalue& eval);

void Eigenorthes (sEigenvalue& eval);

void Eigenhqr2 (sEigenvalue& eval);

int computeEigenvalues3x3(float dout[3], float a[3][3]);


#endif