Fixed sqrt function

packages/math/math.grnd

@@ -184,15 +184,18 @@ endfun
 fun -double !sqrt -double &in
     # Finding sqrt(a) is the same as finding the roots of
     # f(x) = x^2 - a
-    # Using Newton's method: x_(k+1) = x_k - f(x_k)/f'(x_k) = x_k - ((x_k)^2+a)/2(x_k)
+    # Using Newton's method: x_(k+1) = x_k - f(x_k)/f'(x_k) = x_k - ((x_k)^2-a)/2(x_k)
+    set &ans 2
     @loop
         multiply $ans $ans &num
-        add $ans $in &num
+        subtract $num $in &num
 
         multiply $ans 2 &dom
 
         divide $num $dom &store
-        equal $store 0 &store2
+        lesser $store 0.00000001 &store2
+        greater $store -0.00000001 &store3
+        equal $store2 $store3 &store2
         if $store2 %end
 
         subtract $ans $store &ans
@@ -201,3 +204,7 @@ fun -double !sqrt -double &in
     @end
     return $ans
 endfun
+
+pusharg 2.25
+call !sqrt &store
+stdlnout $store