Equation.js/lib/operators.js

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import Equation from 'equation';
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/*
* Operators and Functions
* fn: function used to evaluate value
* format: the format using which arguments are parsed:
* 0 indicates an argument and 1 indicates the operator
* e.g: factorial is 01, add is 010, like 2!, 2+2
* precedence: determines which operators should be evaluated first
* the lower the value, the higher the precedence
* hasExpression: determines if any of the operator arguments are an expression
* This way, arguments will not be solved by equation and instead
* you have to call solve on each argument yourself.
* You get the arguments as parsed arrays sigma(0, 5, 2@) becomes
* sigma(0, 5, [2, '*', '@']). See sigma operator for reference
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*/
export default {
'^': {
fn: (a, b) => Math.pow(a, b),
format: '010',
precedence: 0
},
'*': {
fn: (a, b) => a * b,
format: '010',
precedence: 1
},
'/': {
fn: (a, b) => a / b,
format: '010',
precedence: 1
},
'%': {
fn: (a, b) => a % b,
format: '010',
precedence: 1
},
'\\': {
fn: (a, b) => Math.floor(a / b),
format: '010',
precedence: 1
},
'+': {
fn: (a, b) => a + b,
format: '010',
precedence: 2
},
'-': {
fn: (a, b) => a - b,
format: '010',
precedence: 2
},
'!': {
fn: (a) => {
let sum = 1;
for (var i = 0; i < a; ++i) {
sum *= i;
}
return sum;
},
format: '01',
precedence: 2
},
'log': {
fn: Math.log,
format: '10',
precedence: -1
},
'ln': {
fn: Math.log,
format: '10',
precedence: -1
},
'lg': {
fn: (a) => Math.log(a) / Math.log(2),
format: '10',
precedence: -1
},
'sin': {
fn: Math.sin,
format: '10',
precedence: -1
},
'cos': {
fn: Math.cos,
format: '10',
precedence: -1
},
'tan': {
fn: Math.tan,
format: '10',
precedence: -1
},
'cot': {
fn: Math.cot,
format: '10',
precedence: -1
},
'round': {
fn: Math.round,
format: '10',
precedence: -1
},
'floor': {
fn: Math.floor,
format: '10',
precedence: -1
},
'sigma': {
fn(from, to, expression) {
const expr = expression.join('').replace(/,/g, '');
const regex = new RegExp(ITERATOR_SIGN, 'g');
let sum = 0;
for (let i = from; i <= to; i++) {
sum += Equation.solve(expr.replace(regex, i));
}
return sum;
},
format: '1000',
hasExpression: true,
precedence: -1
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}
};
const ITERATOR_SIGN = '@';