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math: Change Decimal.multiply to operate on Uint classes

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This commit is contained in:
willclarktech 2020-08-19 10:37:15 +01:00
parent 3cbe9e9676
commit 47018d2b6f
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4 changed files with 74 additions and 33 deletions
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5
packages/launchpad/src/gas.ts
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@ -1,4 +1,4 @@
import { Decimal } from "@cosmjs/math";
import { Decimal, Uint53 } from "@cosmjs/math";
import { coins } from "./coins";
import { StdFee } from "./types";
@ -34,8 +34,7 @@ export type GasLimits<T extends Record<string, StdFee>> = {
};
function calculateFee(gasLimit: number, { denom, amount: gasPriceAmount }: GasPrice): StdFee {
const gasLimitDecimal = Decimal.fromUserInput(gasLimit.toString(), gasPriceAmount.fractionalDigits);
const amount = Math.ceil(gasPriceAmount.multiply(gasLimitDecimal).toFloatApproximation());
const amount = Math.ceil(gasPriceAmount.multiply(new Uint53(gasLimit)).toFloatApproximation());
return {
amount: coins(amount, denom),
gas: gasLimit.toString(),

87
packages/math/src/decimal.spec.ts
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@ -1,4 +1,5 @@
import { Decimal } from "./decimal";
import { Uint32, Uint53, Uint64 } from "./integers";
describe("Decimal", () => {
describe("fromAtomics", () => {
@ -212,27 +213,24 @@ describe("Decimal", () => {
});
describe("multiply", () => {
it("returns correct values", () => {
it("returns correct values for Uint32", () => {
const zero = Decimal.fromUserInput("0", 5);
expect(zero.multiply(Decimal.fromUserInput("0", 5)).toString()).toEqual("0");
expect(zero.multiply(Decimal.fromUserInput("1", 5)).toString()).toEqual("0");
expect(zero.multiply(Decimal.fromUserInput("2", 5)).toString()).toEqual("0");
expect(zero.multiply(Decimal.fromUserInput("2.8", 5)).toString()).toEqual("0");
expect(zero.multiply(Decimal.fromUserInput("0.12345", 5)).toString()).toEqual("0");
expect(zero.multiply(new Uint32(0)).toString()).toEqual("0");
expect(zero.multiply(new Uint32(1)).toString()).toEqual("0");
expect(zero.multiply(new Uint32(2)).toString()).toEqual("0");
expect(zero.multiply(new Uint32(4294967295)).toString()).toEqual("0");
const one = Decimal.fromUserInput("1", 5);
expect(one.multiply(Decimal.fromUserInput("0", 5)).toString()).toEqual("0");
expect(one.multiply(Decimal.fromUserInput("1", 5)).toString()).toEqual("1");
expect(one.multiply(Decimal.fromUserInput("2", 5)).toString()).toEqual("2");
expect(one.multiply(Decimal.fromUserInput("2.8", 5)).toString()).toEqual("2.8");
expect(one.multiply(Decimal.fromUserInput("0.12345", 5)).toString()).toEqual("0.12345");
expect(one.multiply(new Uint32(0)).toString()).toEqual("0");
expect(one.multiply(new Uint32(1)).toString()).toEqual("1");
expect(one.multiply(new Uint32(2)).toString()).toEqual("2");
expect(one.multiply(new Uint32(4294967295)).toString()).toEqual("4294967295");
const oneDotFive = Decimal.fromUserInput("1.5", 5);
expect(oneDotFive.multiply(Decimal.fromUserInput("0", 5)).toString()).toEqual("0");
expect(oneDotFive.multiply(Decimal.fromUserInput("1", 5)).toString()).toEqual("1.5");
expect(oneDotFive.multiply(Decimal.fromUserInput("2", 5)).toString()).toEqual("3");
expect(oneDotFive.multiply(Decimal.fromUserInput("2.8", 5)).toString()).toEqual("4.2");
expect(oneDotFive.multiply(Decimal.fromUserInput("0.12345", 5)).toString()).toEqual("0.18517");
expect(oneDotFive.multiply(new Uint32(0)).toString()).toEqual("0");
expect(oneDotFive.multiply(new Uint32(1)).toString()).toEqual("1.5");
expect(oneDotFive.multiply(new Uint32(2)).toString()).toEqual("3");
expect(oneDotFive.multiply(new Uint32(4294967295)).toString()).toEqual("6442450942.5");
// original value remain unchanged
expect(zero.toString()).toEqual("0");
@ -240,15 +238,58 @@ describe("Decimal", () => {
expect(oneDotFive.toString()).toEqual("1.5");
});
it("throws for different fractional digits", () => {
it("returns correct values for Uint53", () => {
const zero = Decimal.fromUserInput("0", 5);
expect(() => zero.multiply(Decimal.fromUserInput("1", 1))).toThrowError(/do not match/i);
expect(() => zero.multiply(Decimal.fromUserInput("1", 2))).toThrowError(/do not match/i);
expect(() => zero.multiply(Decimal.fromUserInput("1", 3))).toThrowError(/do not match/i);
expect(() => zero.multiply(Decimal.fromUserInput("1", 4))).toThrowError(/do not match/i);
expect(zero.multiply(new Uint53(0)).toString()).toEqual("0");
expect(zero.multiply(new Uint53(1)).toString()).toEqual("0");
expect(zero.multiply(new Uint53(2)).toString()).toEqual("0");
expect(zero.multiply(new Uint53(9007199254740991)).toString()).toEqual("0");
expect(() => zero.multiply(Decimal.fromUserInput("1", 6))).toThrowError(/do not match/i);
expect(() => zero.multiply(Decimal.fromUserInput("1", 7))).toThrowError(/do not match/i);
const one = Decimal.fromUserInput("1", 5);
expect(one.multiply(new Uint53(0)).toString()).toEqual("0");
expect(one.multiply(new Uint53(1)).toString()).toEqual("1");
expect(one.multiply(new Uint53(2)).toString()).toEqual("2");
expect(one.multiply(new Uint53(9007199254740991)).toString()).toEqual("9007199254740991");
const oneDotFive = Decimal.fromUserInput("1.5", 5);
expect(oneDotFive.multiply(new Uint53(0)).toString()).toEqual("0");
expect(oneDotFive.multiply(new Uint53(1)).toString()).toEqual("1.5");
expect(oneDotFive.multiply(new Uint53(2)).toString()).toEqual("3");
expect(oneDotFive.multiply(new Uint53(9007199254740991)).toString()).toEqual("13510798882111486.5");
// original value remain unchanged
expect(zero.toString()).toEqual("0");
expect(one.toString()).toEqual("1");
expect(oneDotFive.toString()).toEqual("1.5");
});
it("returns correct values for Uint64", () => {
const zero = Decimal.fromUserInput("0", 5);
expect(zero.multiply(Uint64.fromString("0")).toString()).toEqual("0");
expect(zero.multiply(Uint64.fromString("1")).toString()).toEqual("0");
expect(zero.multiply(Uint64.fromString("2")).toString()).toEqual("0");
expect(zero.multiply(Uint64.fromString("18446744073709551615")).toString()).toEqual("0");
const one = Decimal.fromUserInput("1", 5);
expect(one.multiply(Uint64.fromString("0")).toString()).toEqual("0");
expect(one.multiply(Uint64.fromString("1")).toString()).toEqual("1");
expect(one.multiply(Uint64.fromString("2")).toString()).toEqual("2");
expect(one.multiply(Uint64.fromString("18446744073709551615")).toString()).toEqual(
"18446744073709551615",
);
const oneDotFive = Decimal.fromUserInput("1.5", 5);
expect(oneDotFive.multiply(Uint64.fromString("0")).toString()).toEqual("0");
expect(oneDotFive.multiply(Uint64.fromString("1")).toString()).toEqual("1.5");
expect(oneDotFive.multiply(Uint64.fromString("2")).toString()).toEqual("3");
expect(oneDotFive.multiply(Uint64.fromString("18446744073709551615")).toString()).toEqual(
"27670116110564327422.5",
);
// original value remain unchanged
expect(zero.toString()).toEqual("0");
expect(one.toString()).toEqual("1");
expect(oneDotFive.toString()).toEqual("1.5");
});
});

10
packages/math/src/decimal.ts
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@ -1,5 +1,7 @@
import BN from "bn.js";
import { Uint32, Uint53, Uint64 } from "./integers";
// Too large values lead to massive memory usage. Limit to something sensible.
// The largest value we need is 18 (Ether).
const maxFractionalDigits = 100;
@ -127,12 +129,10 @@ export class Decimal {
/**
* a.multiply(b) returns a*b.
*
* Both values need to have the same fractional digits.
* We only allow multiplication by unsigned integers to avoid rounding errors.
*/
public multiply(b: Decimal): Decimal {
if (this.fractionalDigits !== b.fractionalDigits) throw new Error("Fractional digits do not match");
const factor = new BN(10).pow(new BN(this.data.fractionalDigits));
const product = this.data.atomics.mul(new BN(b.atomics)).div(factor);
public multiply(b: Uint32 | Uint53 | Uint64): Decimal {
const product = this.data.atomics.mul(new BN(b.toString()));
return new Decimal(product.toString(), this.fractionalDigits);
}

5
packages/math/types/decimal.d.ts vendored
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@ -1,3 +1,4 @@
import { Uint32, Uint53, Uint64 } from "./integers";
/**
* A type for arbitrary precision, non-negative decimals.
*
@ -27,9 +28,9 @@ export declare class Decimal {
/**
* a.multiply(b) returns a*b.
*
* Both values need to have the same fractional digits.
* We only allow multiplication by unsigned integers to avoid rounding errors.
*/
multiply(b: Decimal): Decimal;
multiply(b: Uint32 | Uint53 | Uint64): Decimal;
equals(b: Decimal): boolean;
isLessThan(b: Decimal): boolean;
isLessThanOrEqual(b: Decimal): boolean;