/** * Sets tensor elements for specified indices. * This method first computes an eigen-decomposition of the specified * tensor, and then stores the computed eigenvectors and eigenvalues. * The eigenvalues are ordered such that au >= av >= 0. * @param i1 index for 1st dimension. * @param i2 index for 2nd dimension. * @param a11 tensor element a11. * @param a12 tensor element a12. * @param a22 tensor element a22. */ public void setTensor(int i1, int i2, float a11, float a12, float a22) { float[][] aa = { {a11,a12}, {a12,a22} }; float[][] vv = new float[2][2]; float[] ev = new float[2]; Eigen.solveSymmetric22(aa,vv,ev); float[] u = vv[0]; float au = ev[0]; if (au<0.0f) au = 0.0f; float av = ev[1]; if (av<0.0f) av = 0.0f; setEigenvectorU(i1,i2,u); setEigenvalues(i1,i2,au,av); }
public void testSymmetric22() { int nrand = 10000; double[][] v = new double[2][2]; double[] d = new double[2]; for (int irand=0; irand<nrand; ++irand) { double[][] a = randdouble(2,2); a = add(a, transpose(a)); Eigen.solveSymmetric22(a,v,d); check(a,v,d); } }
a[1][0] = g12[i2][i1]; a[1][1] = g22[i2][i1]; Eigen.solveSymmetric22(a,z,e); float u1i = z[0][0]; float u2i = z[0][1];