xref: /libCEED/tests/t317-basis.c (revision 7b87cde0397b48cc601e25bb3ecac5ddabea754c)
1 /// @file
2 /// Test polynomial derivative interpolation in 1D
3 /// \test Test polynomial derivative interpolation in 1D
4 #include <ceed.h>
5 #include <math.h>
6 #include <stdio.h>
7 
8 #define ALEN(a) (sizeof(a) / sizeof((a)[0]))
9 
10 static CeedScalar Eval(CeedScalar x, CeedInt n, const CeedScalar *p) {
11   CeedScalar y = p[n - 1];
12   for (CeedInt i = n - 2; i >= 0; i--) y = y * x + p[i];
13   return y;
14 }
15 
16 int main(int argc, char **argv) {
17   Ceed             ceed;
18   CeedVector       x, x_q, u, u_q;
19   CeedBasis        basis_x_lobatto, basis_u_lobatto, basis_x_gauss, basis_u_gauss;
20   CeedInt          q     = 6;
21   const CeedScalar p[6]  = {1, 2, 3, 4, 5, 6};  // 1 + 2x + 3x^2 + ...
22   const CeedScalar dp[5] = {2, 6, 12, 20, 30};  // 2 + 6x + 12x^2 + ...
23 
24   CeedInit(argv[1], &ceed);
25 
26   CeedVectorCreate(ceed, 2, &x);
27   CeedVectorCreate(ceed, q, &x_q);
28   CeedVectorSetValue(x_q, 0);
29   CeedVectorCreate(ceed, q, &u);
30   CeedVectorSetValue(u, 0);
31   CeedVectorCreate(ceed, q, &u_q);
32 
33   CeedBasisCreateTensorH1Lagrange(ceed, 1, 1, 2, q, CEED_GAUSS_LOBATTO, &basis_x_lobatto);
34   CeedBasisCreateTensorH1Lagrange(ceed, 1, 1, q, q, CEED_GAUSS_LOBATTO, &basis_u_lobatto);
35 
36   {
37     CeedScalar x_array[2];
38 
39     for (int i = 0; i < 2; i++) x_array[i] = CeedIntPow(-1, i + 1);
40     CeedVectorSetArray(x, CEED_MEM_HOST, CEED_COPY_VALUES, x_array);
41   }
42   CeedBasisApply(basis_x_lobatto, 1, CEED_NOTRANSPOSE, CEED_EVAL_INTERP, x, x_q);
43 
44   {
45     const CeedScalar *x_q_array;
46     CeedScalar        u_q_array[q];
47 
48     CeedVectorGetArrayRead(x_q, CEED_MEM_HOST, &x_q_array);
49     for (CeedInt i = 0; i < q; i++) u_q_array[i] = Eval(x_q_array[i], ALEN(p), p);
50     CeedVectorRestoreArrayRead(x_q, &x_q_array);
51     CeedVectorSetArray(u_q, CEED_MEM_HOST, CEED_COPY_VALUES, u_q_array);
52   }
53 
54   // This operation is the identity because the quadrature is collocated
55   CeedBasisApply(basis_u_lobatto, 1, CEED_TRANSPOSE, CEED_EVAL_INTERP, u_q, u);
56 
57   CeedBasisCreateTensorH1Lagrange(ceed, 1, 1, 2, q, CEED_GAUSS, &basis_x_gauss);
58   CeedBasisCreateTensorH1Lagrange(ceed, 1, 1, q, q, CEED_GAUSS, &basis_u_gauss);
59 
60   CeedBasisApply(basis_x_gauss, 1, CEED_NOTRANSPOSE, CEED_EVAL_INTERP, x, x_q);
61   CeedBasisApply(basis_u_gauss, 1, CEED_NOTRANSPOSE, CEED_EVAL_GRAD, u, u_q);
62 
63   {
64     const CeedScalar *x_q_array, *u_q_array;
65 
66     CeedVectorGetArrayRead(x_q, CEED_MEM_HOST, &x_q_array);
67     CeedVectorGetArrayRead(u_q, CEED_MEM_HOST, &u_q_array);
68     for (CeedInt i = 0; i < q; i++) {
69       CeedScalar px = Eval(x_q_array[i], ALEN(dp), dp);
70       if (fabs(u_q_array[i] - px) > 1000. * CEED_EPSILON) printf("%f != %f = p(%f)\n", u_q_array[i], px, x_q_array[i]);
71     }
72     CeedVectorRestoreArrayRead(x_q, &x_q_array);
73     CeedVectorRestoreArrayRead(u_q, &u_q_array);
74   }
75 
76   CeedVectorDestroy(&x);
77   CeedVectorDestroy(&x_q);
78   CeedVectorDestroy(&u);
79   CeedVectorDestroy(&u_q);
80   CeedBasisDestroy(&basis_x_lobatto);
81   CeedBasisDestroy(&basis_u_lobatto);
82   CeedBasisDestroy(&basis_x_gauss);
83   CeedBasisDestroy(&basis_u_gauss);
84   CeedDestroy(&ceed);
85   return 0;
86 }
87