[Scipy-svn] r4784 - trunk/scipy/sparse/sparsetools

[scipy-svn at scipy.org]

Author: wnbell
Date: 2008-10-05 23:29:46 -0500 (Sun, 05 Oct 2008)
New Revision: 4784

Modified:
   trunk/scipy/sparse/sparsetools/csr.h
Log:
added csr_toell()


Modified: trunk/scipy/sparse/sparsetools/csr.h
===================================================================
--- trunk/scipy/sparse/sparsetools/csr.h	2008-10-05 16:55:22 UTC (rev 4783)
+++ trunk/scipy/sparse/sparsetools/csr.h	2008-10-06 04:29:46 UTC (rev 4784)
@@ -381,7 +381,55 @@
 
 
 
+/*
+ * Compute B = A for CSR matrix A, ELL matrix B
+ *
+ * Input Arguments:
+ *   I  n_row         - number of rows in A
+ *   I  n_col         - number of columns in A
+ *   I  Ap[n_row+1]   - row pointer
+ *   I  Aj[nnz(A)]    - column indices
+ *   T  Ax[nnz(A)]    - nonzeros
+ *   I  row_length    - maximum nnz in a row of A
+ *
+ * Output Arguments:
+ *   I  Bj[n_row * row_length]  - column indices
+ *   T  Bx[n_row * row_length]  - nonzeros
+ *
+ * Note:
+ *   Output arrays Bj, Bx must be preallocated
+ *   Duplicate entries in A are not merged.
+ *   Explicit zeros in A are carried over to B.
+ *   Rows with fewer than row_length columns are padded with zeros.
+ *
+ */
+template <class I, class T>
+void csr_toell(const I n_row,
+	           const I n_col, 
+	           const I Ap[], 
+	           const I Aj[], 
+	           const T Ax[],
+               const I row_length,
+	                 I Bj[],
+	                 T Bx[])
+{
+    const I ell_nnz = row_length * n_row;
+    std::fill(Bj, Bj + ell_nnz, 0);
+    std::fill(Bx, Bx + ell_nnz, 0);
 
+    for(I i = 0; i < n_row; i++){
+        I * Bj_row = Bj + row_length * i;
+        T * Bx_row = Bx + row_length * i;
+        for(I jj = Ap[i]; jj < Ap[i+1]; jj++){
+            *Bj_row = Aj[jj];            
+            *Bx_row = Ax[jj];            
+            Bj_row++;
+            Bx_row++;
+        }
+    }
+}
+
+
 /*
  * Compute C = A*B for CSR matrices A,B
  *