sweep.c: Reduce scope of local variables and avoid reusing them.

This makes the code easier to follow, and helps the compiler with
optimisation.

diff --git a/lib/linreg/sweep.c b/lib/linreg/sweep.c
index 0f8c223c7aa5b2e55c8619fba8be93fff679abb4..c218456418c75ccc450d452eeba21f1fcbbf5cda 100644 (file)
--- a/lib/linreg/sweep.c
+++ b/lib/linreg/sweep.c
@@ -75,8 +75,6 @@ reg_sweep (gsl_matrix * A, int last_col)
   if (A->size1 != A->size2)
     return GSL_ENOTSQR;
 
-  double sweep_element;
-  double tmp;
   int i;
   int j;
   int k;
@@ -90,11 +88,10 @@ reg_sweep (gsl_matrix * A, int last_col)
   B = gsl_matrix_alloc (A->size1, A->size2);
   for (k = 0; k < (A->size1 - 1); k++)
     {
-      sweep_element = gsl_matrix_get (A, k, k);
+      const double sweep_element = gsl_matrix_get (A, k, k);
       if (fabs (sweep_element) > GSL_DBL_MIN)
        {
-         tmp = -1.0 / sweep_element;
-         gsl_matrix_set (B, k, k, tmp);
+         gsl_matrix_set (B, k, k, -1.0 / sweep_element);
          /*
            Rows before current row k.
          */
@@ -102,9 +99,8 @@ reg_sweep (gsl_matrix * A, int last_col)
            {
              for (j = i; j < A->size2; j++)
                {
-                 /*
-                   Use only the upper triangle of A.
-                 */
+                 /* Use only the upper triangle of A. */
+                 double tmp;
                  if (j < k)
                    {
                      tmp = gsl_matrix_get (A, i, j) -
@@ -131,7 +127,7 @@ reg_sweep (gsl_matrix * A, int last_col)
          */
          for (j = k + 1; j < A->size1; j++)
            {
-             tmp = gsl_matrix_get (A, k, j) / sweep_element;
+             double tmp = gsl_matrix_get (A, k, j) / sweep_element;
              gsl_matrix_set (B, k, j, tmp);
            }
          /*
@@ -141,7 +137,7 @@ reg_sweep (gsl_matrix * A, int last_col)
            {
              for (j = i; j < A->size2; j++)
                {
-                 tmp = gsl_matrix_get (A, i, j) -
+                 double tmp = gsl_matrix_get (A, i, j) -
                    gsl_matrix_get (A, k, i)
                    * gsl_matrix_get (A, k, j) / sweep_element;
                  gsl_matrix_set (B, i, j, tmp);