From 284683b00dce0c9ae8a7cbbbbb926f013ec88b58 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?B=C3=A5rd=20Skaflestad?= <Bard.Skaflestad@sintef.no>
Date: Thu, 30 Sep 2010 21:37:14 +0000
Subject: [PATCH] Add a routine for allocating a CSR matrix with known number
 of rows   and non-zeros.  Note that this routine is for allocation only.  
 Caller must create and manage sparsity structure if this is being   used in a
 global assembly process.

  This routine finds utility in MsMFEM BF construction.
---
 sparse_sys.c | 32 ++++++++++++++++++++++++++++++++
 sparse_sys.h |  3 +++
 2 files changed, 35 insertions(+)

diff --git a/sparse_sys.c b/sparse_sys.c
index 544b54065..26691a613 100644
--- a/sparse_sys.c
+++ b/sparse_sys.c
@@ -37,6 +37,38 @@ csrmatrix_new_count_nnz(size_t m)
 }
 
 
+/* Allocate CSR matrix, known nnz.  Allocation only.  Caller must
+ * build sparsity structure before using in global assembly.
+ *
+ * Returns fully allocated structure if successful and NULL otherwise. */
+/* ---------------------------------------------------------------------- */
+struct CSRMatrix *
+csrmatrix_new_known_nnz(size_t m, size_t nnz)
+/* ---------------------------------------------------------------------- */
+{
+    struct CSRMatrix *new;
+
+    new = malloc(1 * sizeof *new);
+
+    if (new != NULL) {
+        new->ia = malloc((m + 1) * sizeof *new->ia);
+        new->ja = malloc(nnz     * sizeof *new->ja);
+        new->sa = malloc(nnz     * sizeof *new->sa);
+
+        if ((new->ia == NULL) || (new->ja == NULL) || (new->sa == NULL)) {
+            csrmatrix_delete(new);
+            new = NULL;
+        } else {
+            new->m   = m;
+            new->n   = 0;
+            new->nnz = nnz;
+        }
+    }
+
+    return new;
+}
+
+
 /* ---------------------------------------------------------------------- */
 size_t
 csrmatrix_new_elms_pushback(struct CSRMatrix *A)
diff --git a/sparse_sys.h b/sparse_sys.h
index 481043e95..1671a79d4 100644
--- a/sparse_sys.h
+++ b/sparse_sys.h
@@ -35,6 +35,9 @@ struct CSRMatrix
 struct CSRMatrix *
 csrmatrix_new_count_nnz(size_t m);
 
+struct CSRMatrix *
+csrmatrix_new_known_nnz(size_t m, size_t nnz);
+
 size_t
 csrmatrix_new_elms_pushback(struct CSRMatrix *A);