Maths: fixed small recursion bug

Signed-off-by: Nicola Vigano <nicola.vigano@esrf.fr>

zUtil_Maths/gtMathsSquareNorm.m

@@ -5,7 +5,7 @@ function square_norm = gtMathsSquareNorm(x)
     if (iscell(x))
         square_norm = 0;
         for n = 1:numel(x)
-            square_norm = square_norm + gtMathsSquareNorm(x);
+            square_norm = square_norm + gtMathsSquareNorm(x{n});
         end
     else
         square_norm = gtMathsSumNDVol(x .* x);