strudel/packages/core/fraction.mjs

/*
fraction.mjs - <short description TODO>
Copyright (C) 2022 Strudel contributors - see <https://github.com/tidalcycles/strudel/blob/main/packages/core/fraction.mjs>
This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more details. You should have received a copy of the GNU Affero General Public License along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/

// import Fraction from 'fraction.js';
import { TimeSpan } from './timespan.mjs';

let instances = 0;
let strings = 0;
let fractions = 0;
let numbers = 0;
setInterval(() => {
  console.log(`${instances} calls = ${numbers} numbers + ${fractions} fractions + ${strings} strings`);
  instances = 0;
  strings = 0;
  fractions = 0;
  numbers = 0;
}, 1000);

// http://localhost:3000/#c3RhY2soCiAgImUzLGJiMyxkNCIuc3RydWN0KCJ4KDMsOCwtMSkiKS5vZmYoMS84LHg9PngudHJhbnNwb3NlKDEyKS52ZWxvY2l0eSguMikpLAogICJjMiIuc3RydWN0KCJ4KDQsOCwtMikiKSwKICAiYzMiLnN0cnVjdCgieCgzLDgsLTIpIi5mYXN0KDIpKQopLnNsb3coMikKIC5lY2hvKDQsLjEyNSwuOCkKIC52ZWxvY2l0eShzaW5lLnN0cnVjdCgieCo4IikuYWRkKDMvNSkubXVsKDIvNSkuZmFzdCg4KSkKIC8vIC5waWFub3JvbGwoKQovLyBzdHJ1ZGVsIGRpc2FibGUtaGlnaGxpZ2h0aW5n
// ~400k/s

// this is a "mock" for fraction.js, using just floats without any rational arithmetic
// to test if the performance gets better without fraction.js
// result: it seems to get better but not by much
// the main jankyness remains for some complicated patterns

class Fraction {
  value; // number
  constructor(value) {
    instances++;
    if (value instanceof Fraction) {
      // TODO: return this?
      this.value = value.value;
      fractions++;
    } else if (typeof value === 'string') {
      const [n, d] = value.split('/');
      this.value = n / (d || 1);
      strings++;
    } else if (typeof value !== 'number' || isNaN(value)) {
      console.warn('Fraction got NaN', value);
    } else {
      numbers++;
      this.value = Number(value);
      if (isNaN(this.value)) {
        console.warn('Fraction parsed NaN from', value);
      }
    }
  }
  add(other) {
    return new Fraction(this.value + other);
  }
  sub(other) {
    return new Fraction(this.value - other);
  }
  mul(other) {
    return new Fraction(this.value * other);
  }
  div(other) {
    return new Fraction(this.value / other);
  }
  toString() {
    return this.value + '';
  }
  valueOf() {
    return this.value;
  }
  floor() {
    return new Fraction(Math.floor(this.value));
  }
  abs() {
    return new Fraction(Math.abs(this.value));
  }
  inverse() {
    return new Fraction(1 / this.value);
  }
  compare(other) {
    return this.value - other;
  }
  equals(other) {
    return this.value.valueOf() === other.valueOf();
  }
  // TODO: toFraction
}

// Returns the start of the cycle.
Fraction.prototype.sam = function () {
  return this.floor();
};

// Returns the start of the next cycle.
Fraction.prototype.nextSam = function () {
  // return new Fraction(Math.floor(this.value) + 1);
  return this.sam().add(1);
};

// Returns a TimeSpan representing the begin and end of the Time value's cycle
Fraction.prototype.wholeCycle = function () {
  return new TimeSpan(this.sam(), this.nextSam());
  /*   const begin = Math.floor(this.value);
  const end = begin + 1;
  return new TimeSpan(begin, end); */
};

// The position of a time value relative to the start of its cycle.
Fraction.prototype.cyclePos = function () {
  return this.sub(this.sam());
};

Fraction.prototype.lt = function (other) {
  return this.compare(other) < 0;
};

Fraction.prototype.gt = function (other) {
  return this.compare(other) > 0;
};

Fraction.prototype.lte = function (other) {
  return this.compare(other) <= 0;
};

Fraction.prototype.gte = function (other) {
  return this.compare(other) >= 0;
};

Fraction.prototype.eq = function (other) {
  return this.compare(other) == 0;
};

Fraction.prototype.max = function (other) {
  return this.gt(other) ? this : other;
};

Fraction.prototype.min = function (other) {
  return this.lt(other) ? this : other;
};

Fraction.prototype.show = function () {
  return this.s * this.n + '/' + this.d;
};

Fraction.prototype.or = function (other) {
  return this.eq(0) ? other : this;
};

/* const fraction = (n) => {
  if (typeof n === 'number') {
    // https://github.com/infusion/Fraction.js/#doubles
    // „If you pass a double as it is, Fraction.js will perform a number analysis based on Farey Sequences."
    // „If you want to keep the number as it is, convert it to a string, as the string parser will not perform any further observations“
    
    // -> those farey sequences turn out to make pattern querying ~20 times slower! always use strings!
    // -> still, some optimizations could be done: .mul .div .add .sub calls still use numbers
    n = String(n);
  }
  return Fraction(n);
}; */

const fraction = (n) => new Fraction(n);

export const gcd = (...fractions) => {
  return fractions.reduce((gcd, fraction) => gcd.gcd(fraction), fraction(1));
};

fraction._original = Fraction;

export default fraction;

// "If you concern performance, cache Fraction.js objects and pass arrays/objects.“
// -> tested memoized version, but it's slower than unmemoized, even with repeated evaluation
/* const memo = {};
const memoizedFraction = (n) => {
  if (typeof n === 'number') {
    n = String(n);
  }
  if (memo[n] !== undefined) {
    return memo[n];
  }
  memo[n] = Fraction(n);
  return memo[n];
}; */