1 // Test polynomial interpolation in 1D 2 #include <ceed.h> 3 #include <math.h> 4 5 #define ALEN(a) (sizeof(a) / sizeof((a)[0])) 6 7 static CeedScalar PolyEval(CeedScalar x, CeedInt n, const CeedScalar *p) { 8 CeedScalar y = p[n-1]; 9 for (CeedInt i=n-2; i>=0; i--) y = y*x + p[i]; 10 return y; 11 } 12 13 int main(int argc, char **argv) { 14 Ceed ceed; 15 CeedBasis bxl, bul, bxg, bug; 16 CeedInt Q = 6; 17 const CeedScalar p[] = {1, 2, 3, 4, 5, 6}; // 1 + 2x + 3x^2 + ... 18 const CeedScalar x[] = {-1, 1}; 19 CeedScalar xq[Q], uq[Q], u[Q]; 20 21 CeedInit(argv[1], &ceed); 22 CeedBasisCreateTensorH1Lagrange(ceed, 1, 1, 2, Q, CEED_GAUSS_LOBATTO, &bxl); 23 CeedBasisCreateTensorH1Lagrange(ceed, 1, 1, Q, Q, CEED_GAUSS_LOBATTO, &bul); 24 CeedBasisApply(bxl, 1, CEED_NOTRANSPOSE, CEED_EVAL_INTERP, x, xq); 25 for (CeedInt i=0; i<Q; i++) uq[i] = PolyEval(xq[i], ALEN(p), p); 26 27 // This operation is the identity because the quadrature is collocated 28 CeedBasisApply(bul, 1, CEED_TRANSPOSE, CEED_EVAL_INTERP, uq, u); 29 30 CeedBasisCreateTensorH1Lagrange(ceed, 1, 1, 2, Q, CEED_GAUSS, &bxg); 31 CeedBasisCreateTensorH1Lagrange(ceed, 1, 1, Q, Q, CEED_GAUSS, &bug); 32 CeedBasisApply(bxg, 1, CEED_NOTRANSPOSE, CEED_EVAL_INTERP, x, xq); 33 CeedBasisApply(bug, 1, CEED_NOTRANSPOSE, CEED_EVAL_INTERP, u, uq); 34 for (CeedInt i=0; i<Q; i++) { 35 CeedScalar px = PolyEval(xq[i], ALEN(p), p); 36 if (!(fabs(uq[i] - px) < 1e-14)) { 37 printf("%f != %f=p(%f)\n", uq[i], px, xq[i]); 38 } 39 } 40 41 CeedBasisDestroy(&bxl); 42 CeedBasisDestroy(&bul); 43 CeedBasisDestroy(&bxg); 44 CeedBasisDestroy(&bug); 45 CeedDestroy(&ceed); 46 return 0; 47 } 48