65 lines
1.5 KiB
TypeScript
65 lines
1.5 KiB
TypeScript
/**
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* Convert decimal number to fraction
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*
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* @example
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* ```js
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* dec2Frac(1.25) // Outputs: "1 1/4"
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* ```
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*
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* @param {number} num Number to convert
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* @param maxDen
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* @return {string} Fraction with remainder
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*/
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export function dec2Frac(num: number, maxDen=1000): string {
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let sign = Math.sign(num);
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num = Math.abs(num);
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if (Number.isInteger(num)) return (sign * num) + "";
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let closest = { n: 0, d: 1, diff: Math.abs(num) };
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for (let d = 1; d <= maxDen; d++) {
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let n = Math.round(num * d);
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let diff = Math.abs(num - n / d);
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if (diff < closest.diff) {
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closest = { n, d, diff };
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if (diff < 1e-8) break; // Close enough
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}
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}
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let integer = Math.floor(closest.n / closest.d);
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let numerator = closest.n - integer * closest.d;
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return (sign < 0 ? '-' : '') +
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(integer ? integer + ' ' : '') +
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(numerator ? numerator + '/' + closest.d : '');
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}
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/**
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* Convert fraction to decimal number
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*
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* @example
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* ```js
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* fracToDec('1 1/4') // Outputs: 1.25
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* ```
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*
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* @param {string} frac Fraction to convert
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* @return {number} Faction as a decimal
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*/
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export function fracToDec(frac: string) {
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let split = frac.split(' ');
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const whole = split.length == 2 ? Number(split[0]) : 0;
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split = (<string>split.pop()).split('/');
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return whole + (Number(split[0]) / Number(split[1]));
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}
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/**
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* Add a suffix to a number:
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* 1 = 1st
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* 2 = 2nd
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* 3 = 3rd
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* N = Nth
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* @param {number} n
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* @returns {string}
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*/
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export function numSuffix(n: number): string {
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const s = ['th', 'st', 'nd', 'rd'], v = n % 100;
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return `${n}${s[(v - 20) % 10] || s[v] || s[0]}`;
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}
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