+static double
+get_sum (const struct covariance_matrix *cov, size_t i)
+{
+ size_t k;
+ const struct variable *var;
+ const union value *val = NULL;
+ struct covariance_accumulator ca;
+ struct covariance_accumulator *c;
+
+ assert ( cov != NULL);
+ var = design_matrix_col_to_var (cov->cov, i);
+ if (var != NULL)
+ {
+ if (var_is_alpha (var))
+ {
+ k = design_matrix_var_to_column (cov->cov, var);
+ i -= k;
+ val = cat_subscript_to_value (i, var);
+ }
+ ca.v1 = var;
+ ca.v2 = var;
+ ca.val1 = val;
+ ca.val2 = val;
+ c = (struct covariance_accumulator *) hsh_find (cov->ca, &ca);
+ if (c != NULL)
+ {
+ return c->sum1;
+ }
+ }
+ return 0.0;
+}