xref: /libCEED/tests/t305-basis.c (revision 8ec64e9ae9d5df169dba8c8ee61d8ec8907b8f80)
1 /// @file
2 /// Test Simultaneous Diagonalization
3 /// \test Simultaneous Diagonalization
4 #include <ceed.h>
5 #include <math.h>
6 
7 int main(int argc, char **argv) {
8   Ceed       ceed;
9   CeedInt    P = 4, Q = 4;
10   CeedScalar M[P * P], K[P * P], X[P * P], lambda[P];
11   CeedBasis  basis;
12 
13   CeedInit(argv[1], &ceed);
14 
15   // Create mass, stiffness matrix
16   CeedBasisCreateTensorH1Lagrange(ceed, 1, 1, P, Q, CEED_GAUSS, &basis);
17   const CeedScalar *interp, *grad, *quad_weights;
18   CeedBasisGetInterp(basis, &interp);
19   CeedBasisGetGrad(basis, &grad);
20   CeedBasisGetQWeights(basis, &quad_weights);
21   for (int i = 0; i < P; i++) {
22     for (int j = 0; j < P; j++) {
23       CeedScalar sum_m = 0, sum_k = 0;
24       for (int k = 0; k < Q; k++) {
25         sum_m += interp[P * k + i] * quad_weights[k] * interp[P * k + j];
26         sum_k += grad[P * k + i] * quad_weights[k] * grad[P * k + j];
27       }
28       M[P * i + j] = sum_m;
29       K[P * i + j] = sum_k;
30     }
31   }
32 
33   CeedSimultaneousDiagonalization(ceed, K, M, X, lambda, P);
34 
35   // Check X^T M X = I
36   CeedScalar work[P * P];
37   for (int i = 0; i < P; i++) {
38     for (int j = 0; j < P; j++) {
39       CeedScalar sum = 0;
40       for (int k = 0; k < P; k++) sum += M[P * i + k] * X[P * k + j];
41       work[P * i + j] = sum;
42     }
43   }
44   for (int i = 0; i < P; i++) {
45     for (int j = 0; j < P; j++) {
46       CeedScalar sum = 0;
47       for (int k = 0; k < P; k++) sum += X[P * k + i] * work[P * k + j];
48       M[P * i + j] = sum;
49     }
50   }
51   for (int i = 0; i < P; i++) {
52     for (int j = 0; j < P; j++) {
53       if (fabs(M[P * i + j] - (i == j ? 1.0 : 0.0)) > 100. * CEED_EPSILON) {
54         // LCOV_EXCL_START
55         printf("Error in diagonalization of M [%" CeedInt_FMT ", %" CeedInt_FMT "]: %f != %f\n", i, j, M[P * i + j], (i == j ? 1.0 : 0.0));
56         // LCOV_EXCL_STOP
57       }
58     }
59   }
60 
61   // Check X^T K X = Lamda
62   for (int i = 0; i < P; i++) {
63     for (int j = 0; j < P; j++) {
64       CeedScalar sum = 0;
65       for (int k = 0; k < P; k++) sum += K[P * i + k] * X[P * k + j];
66       work[P * i + j] = sum;
67     }
68   }
69   for (int i = 0; i < P; i++) {
70     for (int j = 0; j < P; j++) {
71       CeedScalar sum = 0;
72       for (int k = 0; k < P; k++) sum += X[P * k + i] * work[P * k + j];
73       K[P * i + j] = sum;
74     }
75   }
76   for (int i = 0; i < P; i++) {
77     for (int j = 0; j < P; j++) {
78       if (fabs(K[P * i + j] - (i == j ? lambda[i] : 0.0)) > 100. * CEED_EPSILON) {
79         // LCOV_EXCL_START
80         printf("Error in diagonalization of K [%" CeedInt_FMT ", %" CeedInt_FMT "]: %f != %f\n", i, j, K[P * i + j], (i == j ? lambda[i] : 0.0));
81         // LCOV_EXCL_STOP
82       }
83     }
84   }
85 
86   CeedBasisDestroy(&basis);
87   CeedDestroy(&ceed);
88   return 0;
89 }
90