Fix nth_root_exact panic on negative even roots - verify with scilab too

Author: sylvestre

src/integer.rs

@@ -156,7 +156,7 @@ impl ExactRoots for BigUint {
 impl ExactRoots for BigInt {
     fn nth_root_exact(&self, n: u32) -> Option<Self> {
         // For even roots of negative numbers, return None instead of panicking
-        if self.is_negative() && n % 2 == 0 {
+        if self.is_negative() && n.is_multiple_of(2) {
             return None;
         }
 

util/validate_with_scilab.sh

@@ -188,46 +188,65 @@ end
 run_rust_test "factorization"
 validate_test "Integer Factorization" 9
 
-# # Test 6: Exact roots
-# echo -e "${BLUE}6. EXACT ROOTS${NC}"
-# run_scilab_test "Exact Roots" '
-# // Perfect squares
-# squares = [1, 4, 9, 16, 25, 36, 49, 64, 81, 100];
-# for i = 1:length(squares)
-#     n = squares(i);
-#     root = sqrt(n);
-#     printf("sqrt(%d) = %d (exact)\n", n, root);
-# end
-
-# // Perfect cubes (positive)
-# cubes_pos = [1, 8, 27, 64, 125];
-# expected_roots_pos = [1, 2, 3, 4, 5];
-# for i = 1:length(cubes_pos)
-#     n = cubes_pos(i);
-#     root = expected_roots_pos(i);
-#     printf("cbrt(%d) = %d (exact)\n", n, root);
-# end
-
-# // Perfect cubes (negative)
-# cubes_neg = [-1, -8, -27, -64, -125];
-# expected_roots_neg = [-1, -2, -3, -4, -5];
-# for i = 1:length(cubes_neg)
-#     n = cubes_neg(i);
-#     root = expected_roots_neg(i);
-#     printf("cbrt(%d) = %d (exact)\n", n, root);
-# end
-
-# // Even roots of negative numbers (should return None)
-# // Test case for issue #25: nth_root_exact panic on negative even roots
-# printf("-1^(1/2) = None (imaginary)\n");
-# printf("-4^(1/2) = None (imaginary)\n");
-# printf("-8^(1/4) = None (imaginary)\n");
-# printf("-16^(1/4) = None (imaginary)\n");
-# printf("-25^(1/2) = None (imaginary)\n");
-# '
-
-# run_rust_test "exact_roots"
-# validate_test "Exact Roots" 25
+# Test 6: Exact roots
+echo -e "${BLUE}6. EXACT ROOTS${NC}"
+run_scilab_test "Exact Roots" '
+// Perfect squares
+squares = [1, 4, 9, 16, 25, 36, 49, 64, 81, 100];
+for i = 1:length(squares)
+    n = squares(i);
+    root = sqrt(n);
+    printf("sqrt(%d) = %d (exact)\n", n, root);
+end
+
+// Perfect cubes (positive)
+cubes_pos = [1, 8, 27, 64, 125];
+expected_roots_pos = [1, 2, 3, 4, 5];
+for i = 1:length(cubes_pos)
+    n = cubes_pos(i);
+    root = expected_roots_pos(i);
+    printf("cbrt(%d) = %d (exact)\n", n, root);
+end
+
+// Perfect cubes (negative)
+cubes_neg = [-1, -8, -27, -64, -125];
+expected_roots_neg = [-1, -2, -3, -4, -5];
+for i = 1:length(cubes_neg)
+    n = cubes_neg(i);
+    root = expected_roots_neg(i);
+    printf("cbrt(%d) = %d (exact)\n", n, root);
+end
+
+// Even roots of negative numbers (should return None)
+// Test case for issue #25: nth_root_exact panic on negative even roots
+printf("-1 nth_root_exact(2) = None\n");
+printf("-4 nth_root_exact(2) = None\n");
+printf("-8 nth_root_exact(4) = None\n");
+printf("-16 nth_root_exact(4) = None\n");
+printf("-25 nth_root_exact(2) = None\n");
+
+// Odd roots of negative numbers (should work)
+printf("-8 nth_root_exact(3) = -2\n");
+printf("-27 nth_root_exact(3) = -3\n");
+printf("-32 nth_root_exact(5) = -2\n");
+
+// Additional nth_root_exact tests for positive numbers
+printf("16 nth_root_exact(4) = 2\n");
+printf("32 nth_root_exact(5) = 2\n");
+printf("81 nth_root_exact(4) = 3\n");
+printf("243 nth_root_exact(5) = 3\n");
+
+// Test various signed integer type limits from patch
+printf("-1i8 nth_root_exact(2) = None\n");
+printf("-1i16 nth_root_exact(2) = None\n");
+printf("-1i32 nth_root_exact(2) = None\n");
+printf("-1i64 nth_root_exact(2) = None\n");
+printf("-1i128 nth_root_exact(2) = None\n");
+printf("-1isize nth_root_exact(2) = None\n");
+'
+
+run_rust_test "exact_roots"
+validate_test "Exact Roots" 31
 
 # Test 7: Large numbers
 echo -e "${BLUE}7. LARGE NUMBERS${NC}"