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fix sqrt(0)

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This commit is contained in:
David Rubin 2023-11-06 13:56:11 -08:00 committed by Veikka Tuominen
parent b3462b7cec
commit 03abac3824
2 changed files with 38 additions and 1 deletions
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13
lib/std/math/big/int.zig
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@ -3228,8 +3228,19 @@ pub const Managed = struct {
/// r = ⌊√a⌋
pub fn sqrt(rma: *Managed, a: *const Managed) !void {
const needed_limbs = calcSqrtLimbsBufferLen(a.bitCountAbs());
const bit_count = a.bitCountAbs();
if (bit_count == 0) {
try rma.set(0);
rma.setMetadata(a.isPositive(), rma.len());
return;
}
if (!a.isPositive()) {
return error.SqrtOfNegativeNumber;
}
const needed_limbs = calcSqrtLimbsBufferLen(bit_count);
const limbs_buffer = try rma.allocator.alloc(Limb, needed_limbs);
defer rma.allocator.free(limbs_buffer);

26
lib/std/math/big/int_test.zig
View File

@ -3149,3 +3149,29 @@ test "big.int.Const.order 0 == -0" {
};
try std.testing.expectEqual(std.math.Order.eq, a.order(b));
}
test "big.int.Managed sqrt(0) = 0" {
const allocator = testing.allocator;
var a = try Managed.initSet(allocator, 1);
defer a.deinit();
var res = try Managed.initSet(allocator, 1);
defer res.deinit();
try a.setString(10, "0");
try res.sqrt(&a);
}
test "big.int.Managed sqrt(-1) = error" {
const allocator = testing.allocator;
var a = try Managed.initSet(allocator, 1);
defer a.deinit();
var res = try Managed.initSet(allocator, 1);
defer res.deinit();
try a.setString(10, "-1");
try testing.expectError(error.SqrtOfNegativeNumber, res.sqrt(&a));
}