104 lines
3.5 KiB
JavaScript
104 lines
3.5 KiB
JavaScript
/**
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* LogarithmPlotter - 2D plotter software to make BODE plots, sequences and distribution functions.
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* Copyright (C) 2021-2024 Ad5001
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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import Latex from "latex.mjs"
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import * as Utils from "../utils.mjs"
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/**
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* Represents any kind of x-based or non variable based expression.
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*/
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export class Expression {
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constructor(expr) {
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if(!Modules.ExprParser)
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throw new Error('Expression parser not initialized.')
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if(!Modules.Objects)
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throw new Error('Objects API not initialized.')
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this.expr = Utils.exponentsToExpression(expr)
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this.calc = Modules.ExprParser.parse(this.expr).simplify()
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this.cached = this.isConstant()
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this.cachedValue = null
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if(this.cached && this.allRequirementsFullfilled())
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this.cachedValue = this.calc.evaluate(Modules.Objects.currentObjectsByName)
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this.latexMarkup = Latex.expression(this.calc.tokens)
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}
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isConstant() {
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let vars = this.calc.variables()
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return !vars.includes("x") && !vars.includes("n")
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}
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requiredObjects() {
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return this.calc.variables().filter(objName => objName !== "x" && objName !== "n")
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}
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allRequirementsFullfilled() {
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return this.requiredObjects().every(objName => objName in Modules.Objects.currentObjectsByName)
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}
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undefinedVariables() {
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return this.requiredObjects().filter(objName => !(objName in Modules.Objects.currentObjectsByName))
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}
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recache() {
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if(this.cached)
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this.cachedValue = this.calc.evaluate(Modules.Objects.currentObjectsByName)
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}
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execute(x = 1) {
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if(this.cached) {
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if(this.cachedValue == null)
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this.cachedValue = this.calc.evaluate(Modules.Objects.currentObjectsByName)
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return this.cachedValue
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}
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Modules.ExprParser.currentVars = Object.assign({'x': x}, Modules.Objects.currentObjectsByName)
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return this.calc.evaluate(Modules.ExprParser.currentVars)
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}
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simplify(x) {
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let expr = this.calc.substitute('x', x).simplify()
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if(expr.evaluate() === 0) return '0'
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let str = Utils.makeExpressionReadable(expr.toString());
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if(str !== undefined && str.match(/^\d*\.\d+$/)) {
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if(str.split('.')[1].split('0').length > 7) {
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// Likely rounding error
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str = parseFloat(str.substring(0, str.length-1)).toString();
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}
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}
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return str
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}
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duplicate() {
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return new Expression(this.toEditableString())
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}
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toEditableString() {
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return this.calc.toString()
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}
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toString(forceSign=false) {
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let str = Utils.makeExpressionReadable(this.calc.toString())
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if(str[0] !== '-' && forceSign) str = '+' + str
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return str
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}
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}
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export function executeExpression(expr){
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return (new Expression(expr.toString())).execute()
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}
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