Tidy: modernize-use-nullptr
[gromacs.git] / src / gromacs / linearalgebra / sparsematrix.cpp
blob79ec5912f09e9d0e51e19ecbddb2b901d11fcd6c
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37 #include "gmxpre.h"
39 #include "sparsematrix.h"
41 #include <stdio.h>
42 #include <stdlib.h>
44 #include <cassert>
46 #include "gromacs/utility/smalloc.h"
48 gmx_sparsematrix_t *
49 gmx_sparsematrix_init(int nrow)
51 int i;
52 gmx_sparsematrix_t *A;
54 snew(A, 1);
56 A->nrow = nrow;
57 snew(A->ndata, nrow);
58 snew(A->nalloc, nrow);
59 snew(A->data, nrow);
61 for (i = 0; i < nrow; i++)
63 A->ndata[i] = 0;
64 A->nalloc[i] = 0;
65 A->data[i] = nullptr;
67 return A;
72 void
73 gmx_sparsematrix_destroy(gmx_sparsematrix_t * A)
75 int i;
77 /* Release each row */
78 for (i = 0; i < A->nrow; i++)
80 if (A->data[i] != nullptr)
82 sfree(A->data[i]);
85 /* Release the rowdata arrays */
86 sfree(A->ndata);
87 sfree(A->nalloc);
88 sfree(A->data);
89 /* Release matrix structure itself */
90 sfree(A);
95 void
96 gmx_sparsematrix_print(FILE * stream,
97 gmx_sparsematrix_t * A)
99 int i, j, k;
101 for (i = 0; i < A->nrow; i++)
103 if (A->ndata[i] == 0)
105 for (j = 0; j < A->nrow; j++)
107 fprintf(stream, " %6.3f", 0.0);
110 else
112 k = 0;
113 for (j = 0; j < A->ndata[i]; j++)
115 while (k++ < A->data[i][j].col)
117 fprintf(stream, " %6.3f", 0.0);
119 fprintf(stream, " %6.3f", A->data[i][j].value);
121 while (k++ < A->nrow)
123 fprintf(stream, " %6.3f", 0.0);
126 fprintf(stream, "\n");
132 real
133 gmx_sparsematrix_value(gmx_sparsematrix_t * A,
134 int row,
135 int col)
137 gmx_bool found = FALSE;
138 int i;
139 real value;
141 assert(row < A->nrow);
143 value = 0;
145 /* Find previous value */
146 for (i = 0; i < A->ndata[row] && (found == FALSE); i++)
148 if (A->data[row][i].col == col)
150 found = TRUE;
151 value = A->data[row][i].value;
155 /* value=0 if we didn't find any match */
156 return value;
161 void
162 gmx_sparsematrix_increment_value(gmx_sparsematrix_t * A,
163 int row,
164 int col,
165 real difference)
167 gmx_bool found = FALSE;
168 int i;
170 assert(row < A->nrow);
172 /* Try to find a previous entry with this row/col */
173 for (i = 0; i < A->ndata[row] && !found; i++)
175 if (A->data[row][i].col == col)
177 found = TRUE;
178 A->data[row][i].value += difference;
182 /* Add a new entry if nothing was found */
183 if (!found)
185 /* add the value at the end of the row */
186 if (A->ndata[row] == A->nalloc[row])
188 A->nalloc[row] += 100;
189 if (A->data[row] == nullptr)
191 snew(A->data[row], A->nalloc[row]);
193 else
195 srenew(A->data[row], A->nalloc[row]);
198 A->data[row][A->ndata[row]].col = col;
199 /* Previous value was 0.0 */
200 A->data[row][A->ndata[row]].value = difference;
201 A->ndata[row]++;
206 /* Routine to compare column values of two entries, used for quicksort of each row.
208 * The data entries to compare are of the type gmx_sparsematrix_entry_t, but quicksort
209 * uses void pointers as arguments, so we cast them back internally.
211 static int
212 compare_columns(const void *v1, const void *v2)
214 int c1 = ((gmx_sparsematrix_entry_t *)v1)->col;
215 int c2 = ((gmx_sparsematrix_entry_t *)v2)->col;
217 if (c1 < c2)
219 return -1;
221 else if (c1 > c2)
223 return 1;
225 else
227 return 0;
232 void
233 gmx_sparsematrix_compress(gmx_sparsematrix_t * A)
235 int i, j;
237 for (i = 0; i < A->nrow; i++)
239 /* Remove last value on this row while it is zero */
240 while (A->ndata[i] > 0 && A->data[i][A->ndata[i]-1].value == 0)
242 A->ndata[i]--;
245 /* Go through values on this row and look for more zero elements */
246 for (j = 0; j < A->ndata[i]; j++)
248 /* If this element was zero, exchange it with the last non-zero
249 * element on the row (yes, this will invalidate the sort order)
251 if (A->data[i][j].value == 0)
253 A->data[i][j].value = A->data[i][A->ndata[i]-1].value;
254 A->data[i][j].col = A->data[i][A->ndata[i]-1].col;
255 A->ndata[i]--;
258 /* Only non-zero elements remaining on this row. Sort them after column index */
259 qsort((void *)(A->data[i]),
260 A->ndata[i],
261 sizeof(gmx_sparsematrix_entry_t),
262 compare_columns);
267 void
268 gmx_sparsematrix_vector_multiply(gmx_sparsematrix_t * A,
269 real * x,
270 real * y)
272 real s, v, xi;
273 int i, j, k;
274 gmx_sparsematrix_entry_t * data; /* pointer to simplify data access */
276 for (i = 0; i < A->nrow; i++)
278 y[i] = 0;
281 if (A->compressed_symmetric)
283 for (i = 0; i < A->nrow; i++)
285 xi = x[i];
286 s = 0.0;
287 data = A->data[i];
289 for (k = 0; k < A->ndata[i]; k++)
291 j = data[k].col;
292 v = data[k].value;
293 s += v * x[j];
294 if (i != j)
296 y[j] += v * xi;
299 y[i] += s;
302 else
304 /* not compressed symmetric storage */
305 for (i = 0; i < A->nrow; i++)
307 s = 0.0;
308 data = A->data[i];
310 for (k = 0; k < A->ndata[i]; k++)
312 j = data[k].col;
313 v = data[k].value;
314 s += v * x[j];
316 y[i] += s;