Overhaul functions in statistics/base directory. Widen input validation to accept logicals. Return correct class of output, e.g., 'single' depending on class of input. Correct or add tests for above. * center.m, cov.m, kendall.m, mean.m, meansq.m, median.m, mode.m, prctile.m, quantile.m, ranks.m, run_count.m, runlength.m, spearman.m, statistics.m, std.m, var.m, logistic_inv.m: Overhaul as described above * corrcoef.m: Overhaul + remove input validation already done by cov(). * cor.m, logit.m, ppplot.m, table.m: Only align test blocks. * gls.m, ols.m: Only correct class of output, no logical inputs for regression. * histc.m: Only change spacing of code to be uniform. * iqr.m: Overhaul + 2X speedup by calling empirical_inv just once. * kurtosis.m: Overhaul + replace repmat instances with center(). * mahalanobis.m: Overhaul + use bsxfun for centering data. * moment.m: Overhaul + replace repmat instances with center(). * probit.m, range.m: Redo input validation and add tests. * skewness.m: Overhaul + replace repmat instances with center(). * zscore.m: Overhaul + replace repmat instances with center() + use bsxfun.

--- a/scripts/statistics/base/gls.m
+++ b/scripts/statistics/base/gls.m
@@ -82,10 +82,21 @@
   if (rx != ry)
     error ("gls: number of rows of X and Y must be equal");
   endif
-  if (!issquare(o) || ro != ry*cy)
+  if (!issquare (o) || ro != ry*cy)
     error ("gls: matrix O must be square matrix with rows = rows (Y) * cols (Y)");
   endif
 
+  if (isinteger (x))
+    x = double (x);
+  endif
+  if (isinteger (y))
+    y = double (y);
+  endif
+  if (isinteger (o))
+    o = double (o);
+  endif
+
+  ## Start of algorithm
   o = o^(-1/2);
   z = kron (eye (cy), x);
   z = o * z;
@@ -116,7 +127,7 @@
 %! y = 3*x + 2;
 %! x = [x, ones(5,1)];
 %! o = diag (ones (5,1));
-%! assert (gls (y,x,o), [3; 2], 50*eps)
+%! assert (gls (y,x,o), [3; 2], 50*eps);
 
 %% Test input validation
 %!error gls ()