diff --git a/linalg-practice.py b/linalg-practice.py
index 681c059..f5e8e18 100644
--- a/linalg-practice.py
+++ b/linalg-practice.py
@@ -7,7 +7,7 @@ errs = (ValueError, TypeError)
 
 def genmatrix(rowcol, intmax, dif) :
     # generate a random matrices
-    a = sp.randMatrix(rowcol, rowcol, 0, intmax)
+    a = sp.randMatrix(rowcol, rowcol, -intmax, intmax)
     # if determinant non-zero, radnom value less than difficulty, set a to its inverse
     if a.det() != 0 and random.random() <= dif :
         a = a.inv()