psychart/dist/pumpchart/lib.js

View air conditions on a psychrometric chart

import * as SMath from 'smath';
/**
 * Find the solution (zero) of a function.
 */
export function zero(func, left, right, epsilon = 1e-6, maxIterations = 1e6) {
    for (let i = 0; i < maxIterations; i++) {
        const funcLeft = func(left);
        const funcRight = func(right);
        if (Number.isNaN(funcLeft)) {
            throw new Error(`f(${left}) is NaN`);
        }
        if (Number.isNaN(funcRight)) {
            throw new Error(`f(${right}) is NaN`);
        }
        const leftSign = Math.sign(funcLeft);
        const rightSign = Math.sign(funcRight);
        if (SMath.approx(funcLeft, 0, epsilon)) {
            return left;
        }
        if (SMath.approx(funcRight, 0, epsilon)) {
            return right;
        }
        if (leftSign === rightSign) {
            throw new Error('A solution cannot be found.');
        }
        const mid = (left + right) / 2;
        const funcMid = func(mid);
        const midSign = Math.sign(funcMid);
        if (SMath.approx(funcMid, 0, epsilon)) {
            return mid;
        }
        if (midSign === leftSign) {
            left = mid;
        }
        else {
            right = mid;
        }
    }
    return (left + right) / 2;
}