xref: /petsc/src/dm/dt/tests/ex9.c (revision f13dfd9ea68e0ddeee984e65c377a1819eab8a8a)
1 const char help[] = "Tests PetscDTPKDEvalJet()";
2 
3 #include <petscdt.h>
4 #include <petscblaslapack.h>
5 
6 static PetscErrorCode testOrthogonality(PetscInt dim, PetscInt deg)
7 {
8   PetscQuadrature  q;
9   const PetscReal *points, *weights;
10   PetscInt         Npoly, npoints, i, j, k;
11   PetscReal       *p;
12 
13   PetscFunctionBegin;
14   PetscCall(PetscDTStroudConicalQuadrature(dim, 1, deg + 1, -1., 1., &q));
15   PetscCall(PetscQuadratureGetData(q, NULL, NULL, &npoints, &points, &weights));
16   PetscCall(PetscDTBinomialInt(dim + deg, dim, &Npoly));
17   PetscCall(PetscMalloc1(Npoly * npoints, &p));
18   PetscCall(PetscDTPKDEvalJet(dim, npoints, points, deg, 0, p));
19   for (i = 0; i < Npoly; i++) {
20     for (j = i; j < Npoly; j++) {
21       PetscReal integral = 0.;
22       PetscReal exact    = (i == j) ? 1. : 0.;
23 
24       for (k = 0; k < npoints; k++) integral += weights[k] * p[i * npoints + k] * p[j * npoints + k];
25       PetscCheck(PetscAbsReal(integral - exact) <= PETSC_SMALL, PETSC_COMM_SELF, PETSC_ERR_PLIB, "<P[%" PetscInt_FMT "], P[%" PetscInt_FMT "]> = %g != delta_{%" PetscInt_FMT ",%" PetscInt_FMT "}", i, j, (double)integral, i, j);
26     }
27   }
28   PetscCall(PetscFree(p));
29   PetscCall(PetscQuadratureDestroy(&q));
30   PetscFunctionReturn(PETSC_SUCCESS);
31 }
32 
33 static PetscErrorCode testDerivativesLegendre(PetscInt dim, PetscInt deg, PetscInt k)
34 {
35   PetscInt         Np, Nk, i, j, l, d, npoints;
36   PetscRandom      rand;
37   PetscReal       *point;
38   PetscReal       *lgndre_coeffs;
39   PetscReal       *pkd_coeffs;
40   PetscReal       *proj;
41   PetscReal      **B;
42   PetscQuadrature  q;
43   PetscReal       *points1d;
44   PetscInt        *degrees;
45   PetscInt        *degtup, *ktup;
46   const PetscReal *points;
47   const PetscReal *weights;
48   PetscReal       *lgndre_jet;
49   PetscReal      **D;
50   PetscReal       *pkd_jet, *pkd_jet_basis;
51 
52   PetscFunctionBegin;
53   PetscCall(PetscDTBinomialInt(dim + deg, dim, &Np));
54   PetscCall(PetscDTBinomialInt(dim + k, dim, &Nk));
55 
56   /* create the projector (because it is an orthonormal basis, the projector is the moment integrals) */
57   PetscCall(PetscDTStroudConicalQuadrature(dim, 1, deg + 1, -1., 1., &q));
58   PetscCall(PetscQuadratureGetData(q, NULL, NULL, &npoints, &points, &weights));
59   PetscCall(PetscMalloc1(npoints * Np, &proj));
60   PetscCall(PetscDTPKDEvalJet(dim, npoints, points, deg, 0, proj));
61   for (i = 0; i < Np; i++)
62     for (j = 0; j < npoints; j++) proj[i * npoints + j] *= weights[j];
63 
64   PetscCall(PetscRandomCreate(PETSC_COMM_SELF, &rand));
65   PetscCall(PetscRandomSetInterval(rand, -1., 1.));
66 
67   /* create a random coefficient vector */
68   PetscCall(PetscMalloc2(Np, &lgndre_coeffs, Np, &pkd_coeffs));
69   for (i = 0; i < Np; i++) PetscCall(PetscRandomGetValueReal(rand, &lgndre_coeffs[i]));
70 
71   PetscCall(PetscMalloc2(dim, &degtup, dim, &ktup));
72   PetscCall(PetscMalloc1(deg + 1, &degrees));
73   for (i = 0; i < deg + 1; i++) degrees[i] = i;
74 
75   /* project the lgndre_coeffs to pkd_coeffs */
76   PetscCall(PetscArrayzero(pkd_coeffs, Np));
77   PetscCall(PetscMalloc1(npoints, &points1d));
78   PetscCall(PetscMalloc1(dim, &B));
79   for (d = 0; d < dim; d++) {
80     PetscCall(PetscMalloc1((deg + 1) * npoints, &B[d]));
81     /* get this coordinate */
82     for (i = 0; i < npoints; i++) points1d[i] = points[i * dim + d];
83     PetscCall(PetscDTLegendreEval(npoints, points1d, deg + 1, degrees, B[d], NULL, NULL));
84   }
85   PetscCall(PetscFree(points1d));
86   for (i = 0; i < npoints; i++) {
87     PetscReal val = 0.;
88 
89     for (j = 0; j < Np; j++) {
90       PetscReal mul  = lgndre_coeffs[j];
91       PetscReal valj = 1.;
92 
93       PetscCall(PetscDTIndexToGradedOrder(dim, j, degtup));
94       for (l = 0; l < dim; l++) valj *= B[l][i * (deg + 1) + degtup[l]];
95       val += mul * valj;
96     }
97     for (j = 0; j < Np; j++) pkd_coeffs[j] += proj[j * npoints + i] * val;
98   }
99   for (i = 0; i < dim; i++) PetscCall(PetscFree(B[i]));
100   PetscCall(PetscFree(B));
101 
102   /* create a random point in the biunit simplex */
103   PetscCall(PetscMalloc1(dim, &point));
104   for (i = 0; i < dim; i++) PetscCall(PetscRandomGetValueReal(rand, &point[i]));
105   for (i = dim - 1; i > 0; i--) {
106     PetscReal val = point[i];
107     PetscInt  j;
108 
109     for (j = 0; j < i; j++) point[j] = (point[j] + 1.) * (1. - val) * 0.5 - 1.;
110   }
111 
112   PetscCall(PetscMalloc3(Nk * Np, &pkd_jet_basis, Nk, &lgndre_jet, Nk, &pkd_jet));
113   /* evaluate the jet at the point with PKD polynomials */
114   PetscCall(PetscDTPKDEvalJet(dim, 1, point, deg, k, pkd_jet_basis));
115   for (i = 0; i < Nk; i++) {
116     PetscReal val = 0.;
117     for (j = 0; j < Np; j++) val += pkd_coeffs[j] * pkd_jet_basis[j * Nk + i];
118     pkd_jet[i] = val;
119   }
120 
121   /* evaluate the 1D jets of the Legendre polynomials */
122   PetscCall(PetscMalloc1(dim, &D));
123   for (i = 0; i < dim; i++) {
124     PetscCall(PetscMalloc1((deg + 1) * (k + 1), &D[i]));
125     PetscCall(PetscDTJacobiEvalJet(0., 0., 1, &point[i], deg, k, D[i]));
126   }
127   /* compile the 1D Legendre jets into the tensor Legendre jet */
128   for (j = 0; j < Nk; j++) lgndre_jet[j] = 0.;
129   for (i = 0; i < Np; i++) {
130     PetscReal mul = lgndre_coeffs[i];
131 
132     PetscCall(PetscDTIndexToGradedOrder(dim, i, degtup));
133     for (j = 0; j < Nk; j++) {
134       PetscReal val = 1.;
135 
136       PetscCall(PetscDTIndexToGradedOrder(dim, j, ktup));
137       for (l = 0; l < dim; l++) val *= D[l][degtup[l] * (k + 1) + ktup[l]];
138       lgndre_jet[j] += mul * val;
139     }
140   }
141   for (i = 0; i < dim; i++) PetscCall(PetscFree(D[i]));
142   PetscCall(PetscFree(D));
143 
144   for (i = 0; i < Nk; i++) {
145     PetscReal diff  = lgndre_jet[i] - pkd_jet[i];
146     PetscReal scale = 1. + PetscAbsReal(lgndre_jet[i]) + PetscAbsReal(pkd_jet[i]);
147     PetscReal tol   = 10. * PETSC_SMALL * scale;
148 
149     PetscCheck(PetscAbsReal(diff) <= tol, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Jet mismatch between PKD and tensor Legendre bases: error %g at tolerance %g", (double)diff, (double)tol);
150   }
151 
152   PetscCall(PetscFree2(degtup, ktup));
153   PetscCall(PetscFree(degrees));
154   PetscCall(PetscFree3(pkd_jet_basis, lgndre_jet, pkd_jet));
155   PetscCall(PetscFree(point));
156   PetscCall(PetscFree2(lgndre_coeffs, pkd_coeffs));
157   PetscCall(PetscFree(proj));
158   PetscCall(PetscRandomDestroy(&rand));
159   PetscCall(PetscQuadratureDestroy(&q));
160   PetscFunctionReturn(PETSC_SUCCESS);
161 }
162 
163 int main(int argc, char **argv)
164 {
165   PetscInt dim, deg, k;
166 
167   PetscFunctionBeginUser;
168   PetscCall(PetscInitialize(&argc, &argv, NULL, help));
169   dim = 3;
170   deg = 4;
171   k   = 3;
172   PetscOptionsBegin(PETSC_COMM_WORLD, "", "Options for PetscDTPKDEval() tests", "none");
173   PetscCall(PetscOptionsInt("-dim", "Dimension of the simplex", "ex9.c", dim, &dim, NULL));
174   PetscCall(PetscOptionsInt("-degree", "The degree of the polynomial space", "ex9.c", deg, &deg, NULL));
175   PetscCall(PetscOptionsInt("-k", "The number of derivatives to use in the taylor test", "ex9.c", k, &k, NULL));
176   PetscOptionsEnd();
177   PetscCall(testOrthogonality(dim, deg));
178   PetscCall(testDerivativesLegendre(dim, deg, k));
179   PetscCall(PetscFinalize());
180   return 0;
181 }
182 
183 /*TEST
184 
185   test:
186     args: -dim {{1 2 3 4}}
187 
188 TEST*/
189