new file mode 100644
--- /dev/null
+++ b/scripts/linear-algebra/rank.m
@@ -0,0 +1,25 @@
+function retval = rank (A, tol)
+
+# usage: rand (a, tol)
+#
+# Return the rank of the matrix a.  The rank is taken to be the number
+# of singular values of a that are greater than tol.
+#
+# If the second argument is omitted, it is taken to be
+#
+#   tol =  max (size (a)) * sigma (1) * eps;
+#
+# where eps is machine precision and sigma is the largest singular
+# value of a.
+
+  if (nargin == 1)
+    sigma = svd (A);
+    tolerance = max (size (A)) * sigma (1) * eps;
+  elseif (nargin == 2)
+    tolerance = tol;
+  else
+    error ("usage: rank (A)");
+  endif
+  retval = sum (sigma > tolerance);
+
+endfunction