sqrt(a) no longer supports an additional argument for n (n=2 by default).

src/rules/powers.py

@@ -249,27 +249,31 @@ MESSAGES[remove_negative_root] = _('{0[1]} is an odd number, so apply the ' \
 
 def match_exponent_to_root(node):
     """
-    a^(1 / m)  ->  sqrt(a, m)
-    a^(n / m)  ->  sqrt(a^n, m)
+    a^(1 / 2)  ->  sqrt(a)
+    a^(n / 2)  ->  sqrt(a^n)
     """
     assert node.is_op(OP_POW)
 
     left, right = node
 
-    if right.is_op(OP_DIV):
-        return [P(node, exponent_to_root, (left,) + tuple(right))]
+    if right.is_op(OP_DIV) and right[1] == 2:
+        return [P(node, exponent_to_root)]
 
     return []
 
 
 def exponent_to_root(root, args):
     """
-    a^(1 / m)  ->  sqrt(a, m)
-    a^(n / m)  ->  sqrt(a^n, m)
+    a^(1 / 2)  ->  sqrt(a)
+    a^(n / 2)  ->  sqrt(a^n)
     """
-    a, n, m = args
+    a, (n, _) = root
 
-    return N(OP_SQRT, a if n == 1 else a ** n, m)
+    return N(OP_SQRT, a if n == 1 else a ** n)
+
+
+MESSAGES[exponent_to_root] = \
+        _('Rewrite power with exponent {0[1]} to a square root.')
 
 
 def match_extend_exponent(node):

src/rules/sqrt.py

@@ -88,7 +88,7 @@ def quadrant_sqrt(root, args):
 
 
 MESSAGES[quadrant_sqrt] = \
-        _('The square root of a quadrant reduces to the raised root.')
+        _('The root of a  reduces to the raised root.')
 
 
 def constant_sqrt(root, args):

tests/test_rules_powers.py

@@ -140,17 +140,13 @@ class TestRulesPowers(RulesTestCase):
                  P(root, remove_negative_root)])
 
     def test_match_exponent_to_root(self):
-        a, n, m, l1 = tree('a,n,m,1')
+        root = tree('a ^ (1 / 2)')
+        self.assertEqualPos(match_exponent_to_root(root),
+                [P(root, exponent_to_root)])
 
-        root = a ** (n / m)
-        possibilities = match_exponent_to_root(root)
-        self.assertEqualPos(possibilities,
-                [P(root, exponent_to_root, (a, n, m))])
-
-        root = a ** (l1 / m)
-        possibilities = match_exponent_to_root(root)
-        self.assertEqualPos(possibilities,
-                [P(root, exponent_to_root, (a, 1, m))])
+        root = tree('a ^ (n / 2)')
+        self.assertEqualPos(match_exponent_to_root(root),
+                [P(root, exponent_to_root)])
 
     def test_add_exponents(self):
         a, p, q = tree('a,p,q')
@@ -198,14 +194,11 @@ class TestRulesPowers(RulesTestCase):
         self.assertEqualNodes(remove_negative_root(root, ()), expect)
 
     def test_exponent_to_root(self):
-        a, n, m, l1 = tree('a,n,m,1')
-        root = a ** (n / m)
-
-        self.assertEqualNodes(exponent_to_root(root, (a, n, m)),
-                              N('sqrt', a ** n, m))
+        root, expect = tree('a ^ (1 / 2), sqrt(a)')
+        self.assertEqualNodes(exponent_to_root(root, ()), expect)
 
-        self.assertEqualNodes(exponent_to_root(root, (a, l1, m)),
-                              N('sqrt', a, m))
+        root, expect = tree('a ^ (n / 2), sqrt(a ^ n)')
+        self.assertEqualNodes(exponent_to_root(root, ()), expect)
 
     def test_match_constant_exponent(self):
         a0, a1, a2 = tree('a ^ 0, a ^ 1, a ^ 2')