78 lines
2.5 KiB
JavaScript
78 lines
2.5 KiB
JavaScript
/**
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* LogarithmPlotter - 2D plotter software to make BODE plots, sequences and distribution functions.
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* Copyright (C) 2022 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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.pragma library
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.import "common.js" as C
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.import "latex.js" as Latex
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.import "../utils.js" as Utils
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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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class Expression {
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constructor(expr) {
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this.expr = expr
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this.calc = C.parser.parse(expr).simplify()
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this.cached = this.isConstant()
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this.cachedValue = this.cached ? this.calc.evaluate(C.evalVariables) : null
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this.latexMarkup = Latex.expressionToLatex(this.calc.tokens)
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}
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isConstant() {
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return !this.expr.includes("x") && !this.expr.includes("n")
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}
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execute(x = 1) {
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if(this.cached) return this.cachedValue
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C.currentVars = Object.assign({'x': x}, C.evalVariables)
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return this.calc.evaluate(C.currentVars)
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}
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simplify(x) {
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var expr = this.calc.substitute('x', x).simplify()
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if(expr.evaluate(C.evalVariables) == 0) return '0'
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var 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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var 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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function executeExpression(expr){
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return (new Expression(expr.toString())).execute()
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}
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