WIP

Author: jessealama

src/Decimal128.mts

@@ -1134,6 +1134,10 @@ export class Decimal128 {
             return this.clone();
         }
 
+        if (d.isZero()) {
+            return new Decimal128(NAN);
+        }
+
         if (this.cmp(d) === -1) {
             return this.clone();
         }

src/Rational.mts

@@ -2,6 +2,7 @@ import {
     countFractionalDigits,
     countSignificantDigits,
     Digit,
+    ROUNDING_MODE_TRUNCATE,
     RoundingMode,
 } from "./common.mjs";
 
@@ -423,24 +424,19 @@ export class Rational {
             );
         }
 
-        if (this.isNegative) {
-            return this.negate().round(numFractionalDigits, mode).negate();
-        }
-
         if (numFractionalDigits > 1) {
             return this.scale10(1)
                 .round(numFractionalDigits - 1, mode)
                 .scale10(-1);
         }
-
-        if (mode !== "halfEven") {
-            throw new RangeError("Only half-even rounding mode is supported");
-        }
-
         let s = this.toFixed(1);
 
         let [integerPart, fractionalPart] = s.split(".");
 
+        if (mode === ROUNDING_MODE_TRUNCATE) {
+            return Rational.fromString(integerPart);
+        }
+
         let penultimateDigit = parseInt(
             integerPart.charAt(integerPart.length - 1)
         ) as Digit;

src/common.mts

@@ -42,11 +42,11 @@ export function countFractionalDigits(s: string): number {
 export type Digit = -1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9; // -1 signals that we're moving from the integer part to the decimal part of a decimal number
 export type DigitOrTen = Digit | 10;
 
-const ROUNDING_MODE_CEILING = "ceil";
-const ROUNDING_MODE_FLOOR = "floor";
-const ROUNDING_MODE_TRUNCATE = "trunc";
-const ROUNDING_MODE_HALF_EVEN = "halfEven";
-const ROUNDING_MODE_HALF_EXPAND = "halfExpand";
+export const ROUNDING_MODE_CEILING = "ceil";
+export const ROUNDING_MODE_FLOOR = "floor";
+export const ROUNDING_MODE_TRUNCATE = "trunc";
+export const ROUNDING_MODE_HALF_EVEN = "halfEven";
+export const ROUNDING_MODE_HALF_EXPAND = "halfExpand";
 
 export type RoundingMode =
     | "ceil"

tests/Decimal128/remainder.test.js

@@ -123,7 +123,7 @@ describe("examples from the General Decimal Arithmetic Specification", () => {
         expect(
             new Decimal128("3.6")
                 .remainder(new Decimal128("1.3"))
-                .toString({ normalize: false })
+                .toString({ preserveTrailingZeroes: true })
         ).toStrictEqual("1.0");
     });
 });

tests/Rational/rational.test.js

@@ -31,8 +31,8 @@ describe("toString", () => {
 describe("toFixed", () => {
     test("zero", () => {
         let d = new Rational(0n, 1n);
-        expect(d.toFixed(1)).toStrictEqual("0");
-        expect(d.toFixed(5)).toStrictEqual("0");
+        expect(d.toFixed(1)).toStrictEqual("0.0");
+        expect(d.toFixed(5)).toStrictEqual("0.00000");
     });
     test("exactly representable", () => {
         expect(new Rational(3n, 2n).toFixed(1)).toStrictEqual("1.5");