xref: /libCEED/tests/t317-basis.c (revision 72d852595123308417bcd99e2ca111c71d29cbff)
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 
7 #define ALEN(a) (sizeof(a) / sizeof((a)[0]))
8 
9 static CeedScalar PolyEval(CeedScalar x, CeedInt n, const CeedScalar *p) {
10   CeedScalar y = p[n-1];
11   for (CeedInt i=n-2; i>=0; i--) y = y*x + p[i];
12   return y;
13 }
14 
15 int main(int argc, char **argv) {
16   Ceed ceed;
17   CeedVector X, X_q, U, U_q;
18   CeedBasis basis_x_lobatto, basis_u_lobatto, basis_x_gauss, basis_u_gauss;
19   CeedInt Q = 6;
20   const CeedScalar p[6] = {1, 2, 3, 4, 5, 6}; // 1 + 2x + 3x^2 + ...
21   const CeedScalar dp[5] = {2, 6, 12, 20, 30}; // 2 + 6x + 12x^2 + ...
22   const CeedScalar *xq, *uuq;
23   CeedScalar x[2], uq[Q];
24 
25   CeedInit(argv[1], &ceed);
26 
27   CeedVectorCreate(ceed, 2, &X);
28   CeedVectorCreate(ceed, Q, &X_q);
29   CeedVectorSetValue(X_q, 0);
30   CeedVectorCreate(ceed, Q, &U);
31   CeedVectorSetValue(U, 0);
32   CeedVectorCreate(ceed, Q, &U_q);
33 
34   CeedBasisCreateTensorH1Lagrange(ceed, 1,  1, 2, Q, CEED_GAUSS_LOBATTO,
35                                   &basis_x_lobatto);
36   CeedBasisCreateTensorH1Lagrange(ceed, 1, 1, Q, Q, CEED_GAUSS_LOBATTO,
37                                   &basis_u_lobatto);
38 
39   for (int i = 0; i < 2; i++)
40     x[i] = CeedIntPow(-1, i+1);
41   CeedVectorSetArray(X, CEED_MEM_HOST, CEED_USE_POINTER, (CeedScalar *)&x);
42 
43   CeedBasisApply(basis_x_lobatto, 1, CEED_NOTRANSPOSE, CEED_EVAL_INTERP, X, X_q);
44 
45   CeedVectorGetArrayRead(X_q, CEED_MEM_HOST, &xq);
46   for (CeedInt i=0; i<Q; i++)
47     uq[i] = PolyEval(xq[i], ALEN(p), p);
48   CeedVectorRestoreArrayRead(X_q, &xq);
49   CeedVectorSetArray(U_q, CEED_MEM_HOST, CEED_USE_POINTER, (CeedScalar *)&uq);
50 
51   // This operation is the identity because the quadrature is collocated
52   CeedBasisApply(basis_u_lobatto, 1, CEED_TRANSPOSE, CEED_EVAL_INTERP, U_q, U);
53 
54   CeedBasisCreateTensorH1Lagrange(ceed, 1, 1, 2, Q, CEED_GAUSS, &basis_x_gauss);
55   CeedBasisCreateTensorH1Lagrange(ceed, 1, 1, Q, Q, CEED_GAUSS, &basis_u_gauss);
56 
57   CeedBasisApply(basis_x_gauss, 1, CEED_NOTRANSPOSE, CEED_EVAL_INTERP, X, X_q);
58   CeedBasisApply(basis_u_gauss, 1, CEED_NOTRANSPOSE, CEED_EVAL_GRAD, U, U_q);
59 
60   CeedVectorGetArrayRead(X_q, CEED_MEM_HOST, &xq);
61   CeedVectorGetArrayRead(U_q, CEED_MEM_HOST, &uuq);
62   for (CeedInt i=0; i<Q; i++) {
63     CeedScalar px = PolyEval(xq[i], ALEN(dp), dp);
64     if (fabs(uuq[i] - px) > 1000.*CEED_EPSILON)
65       // LCOV_EXCL_START
66       printf("%f != %f = p(%f)\n", uuq[i], px, xq[i]);
67     // LCOV_EXCL_STOP
68   }
69   CeedVectorRestoreArrayRead(X_q, &xq);
70   CeedVectorRestoreArrayRead(U_q, &uuq);
71 
72   CeedVectorDestroy(&X);
73   CeedVectorDestroy(&X_q);
74   CeedVectorDestroy(&U);
75   CeedVectorDestroy(&U_q);
76   CeedBasisDestroy(&basis_x_lobatto);
77   CeedBasisDestroy(&basis_u_lobatto);
78   CeedBasisDestroy(&basis_x_gauss);
79   CeedBasisDestroy(&basis_u_gauss);
80   CeedDestroy(&ceed);
81   return 0;
82 }
83