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authorEric Andersen <andersen@codepoet.org>2001-05-10 00:40:28 +0000
committerEric Andersen <andersen@codepoet.org>2001-05-10 00:40:28 +0000
commit1077fa4d772832f77a677ce7fb7c2d513b959e3f (patch)
tree579bee13fb0b58d2800206366ec2caecbb15f3fc /libm/double/minv.c
parent22358dd7ce7bb49792204b698f01a6f69b9c8e08 (diff)
uClibc now has a math library. muahahahaha!
-Erik
Diffstat (limited to 'libm/double/minv.c')
-rw-r--r--libm/double/minv.c61
1 files changed, 61 insertions, 0 deletions
diff --git a/libm/double/minv.c b/libm/double/minv.c
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+/* minv.c
+ *
+ * Matrix inversion
+ *
+ *
+ *
+ * SYNOPSIS:
+ *
+ * int n, errcod;
+ * double A[n*n], X[n*n];
+ * double B[n];
+ * int IPS[n];
+ * int minv();
+ *
+ * errcod = minv( A, X, n, B, IPS );
+ *
+ *
+ *
+ * DESCRIPTION:
+ *
+ * Finds the inverse of the n by n matrix A. The result goes
+ * to X. B and IPS are scratch pad arrays of length n.
+ * The contents of matrix A are destroyed.
+ *
+ * The routine returns nonzero on error; error messages are printed
+ * by subroutine simq().
+ *
+ */
+
+minv( A, X, n, B, IPS )
+double A[], X[];
+int n;
+double B[];
+int IPS[];
+{
+double *pX;
+int i, j, k;
+
+for( i=1; i<n; i++ )
+ B[i] = 0.0;
+B[0] = 1.0;
+/* Reduce the matrix and solve for first right hand side vector */
+pX = X;
+k = simq( A, B, pX, n, 1, IPS );
+if( k )
+ return(-1);
+/* Solve for the remaining right hand side vectors */
+for( i=1; i<n; i++ )
+ {
+ B[i-1] = 0.0;
+ B[i] = 1.0;
+ pX += n;
+ k = simq( A, B, pX, n, -1, IPS );
+ if( k )
+ return(-1);
+ }
+/* Transpose the array of solution vectors */
+mtransp( n, X, X );
+return(0);
+}
+