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[Bug-gsl] [bug #51951] sparse add function gives wrong result (shorter t
From: |
Alfredo Correa |
Subject: |
[Bug-gsl] [bug #51951] sparse add function gives wrong result (shorter than expected) |
Date: |
Wed, 6 Sep 2017 03:17:22 -0400 (EDT) |
User-agent: |
Mozilla/5.0 (X11; Fedora; Linux x86_64; rv:55.0) Gecko/20100101 Firefox/55.0 |
URL:
<http://savannah.gnu.org/bugs/?51951>
Summary: sparse add function gives wrong result (shorter than
expected)
Project: GNU Scientific Library
Submitted by: alfc
Submitted on: Wed 06 Sep 2017 07:17:21 AM UTC
Category: Runtime error
Severity: 3 - Normal
Operating System: linux fedora 26
Status: None
Assigned to: None
Open/Closed: Open
Release: 2.3
Discussion Lock: Any
_______________________________________________________
Details:
This program produces the wrong sum D = C + C:
C is
```
matrix in compressed row format:
i = [ 2, 3, 0, 2, 0, 1, 3, 0, ]
p = [ 0, 2, 4, 4, 7, 8, ]
d = [ 3.1, 4.6, 1, 7.2, 2.1, 2.9, 8.5, 4.1, ]
```
while D (erroneously) results in
```
D matrix in compressed row format:
i = [ 2, 3, 0, 1, ]
p = [ 0, 2, 3, 3, 4, 4, ]
d = [ 6.2, 9.2, 2, 5.8, ]
```
```
int main(){
gsl_spmatrix *A = gsl_spmatrix_alloc(5, 4); /* triplet format */
gsl_spmatrix *B, *C, *D;
size_t i, j;
/* build the sparse matrix */
gsl_spmatrix_set(A, 0, 2, 3.1);
gsl_spmatrix_set(A, 0, 3, 4.6);
gsl_spmatrix_set(A, 1, 0, 1.0);
gsl_spmatrix_set(A, 1, 2, 7.2);
gsl_spmatrix_set(A, 3, 0, 2.1);
gsl_spmatrix_set(A, 3, 1, 2.9);
gsl_spmatrix_set(A, 3, 3, 8.5);
gsl_spmatrix_set(A, 4, 0, 4.1);
printf("printing all matrix elements:\n");
for (i = 0; i < 5; ++i)
for (j = 0; j < 4; ++j)
printf("A(%zu,%zu) = %g\n", i, j,
gsl_spmatrix_get(A, i, j));
/* print out elements in triplet format */
printf("matrix in triplet format (i,j,Aij):\n");
gsl_spmatrix_fprintf(stdout, A, "%.1f");
/* convert to compressed row format */
C = gsl_spmatrix_crs(A);
D = gsl_spmatrix_crs(A);
gsl_spmatrix_add(D, C, C);
printf("matrix in compressed row format:\n");
printf("i = [ ");
for (i = 0; i < C->nz; ++i)
printf("%zu, ", C->i[i]);
printf("]\n");
printf("p = [ ");
for (i = 0; i < C->size1 + 1; ++i)
printf("%zu, ", C->p[i]);
printf("]\n");
printf("d = [ ");
for (i = 0; i < C->nz; ++i)
printf("%g, ", C->data[i]);
printf("]\n");
printf("D matrix in compressed row format:\n");
printf("i = [ ");
for (i = 0; i < D->nz; ++i)
printf("%zu, ", D->i[i]);
printf("]\n");
printf("p = [ ");
for (i = 0; i < D->size1 + 1; ++i)
printf("%zu, ", D->p[i]);
printf("]\n");
printf("d = [ ");
for (i = 0; i < D->nz; ++i)
printf("%g, ", D->data[i]);
printf("]\n");
gsl_spmatrix_free(A);
gsl_spmatrix_free(B);
gsl_spmatrix_free(C);
```
_______________________________________________________
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<http://savannah.gnu.org/bugs/?51951>
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- [Bug-gsl] [bug #51951] sparse add function gives wrong result (shorter than expected),
Alfredo Correa <=