use single quotes for matlab compatibility

Author: rasmusbergpalm

DBN/rbmtrain.m

@@ -1,6 +1,6 @@
 function rbm = rbmtrain(rbm, x, opts)
     assert(isfloat(x), 'x must be a float');
-    assert(all(x>=0) && all(x<=1), "all data in x must be in [0:1]");
+    assert(all(x>=0) && all(x<=1), 'all data in x must be in [0:1]');
     m = size(x, 1);
     numbatches = m / opts.batchsize;