107 lines
3.6 KiB
JavaScript
107 lines
3.6 KiB
JavaScript
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// units
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// load math.js (using node.js)
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var math = require('../index');
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// units can be created by providing a value and unit name, or by providing
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// a string with a valued unit.
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console.log('create units');
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var a = math.unit(45, 'cm');
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var b = math.unit('0.1m');
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print(a); // 450 mm
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print(b); // 100 mm
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console.log();
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// units can be added, subtracted, and multiplied or divided by numbers and by other units
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console.log('perform operations');
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print(math.add(a, b)); // 0.55 m
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print(math.multiply(b, 2)); // 200 mm
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print(math.divide(math.unit('1 m'), math.unit('1 s'))); // 1 m / s
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print(math.pow(math.unit('12 in'), 3)); // 1728 in^3
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console.log();
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// units can be converted to a specific type, or to a number
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console.log('convert to another type or to a number');
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print(b.to('cm')); // 10 cm Alternatively: math.to(b, 'cm')
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print(math.to(b, 'inch')); // 3.9370... inch
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print(b.toNumber('cm')); // 10
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print(math.number(b, 'cm')); // 10
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console.log();
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// the expression parser supports units too
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console.log('parse expressions');
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print(math.eval('2 inch to cm')); // 5.08 cm
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print(math.eval('cos(45 deg)')); // 0.70711...
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print(math.eval('90 km/h to m/s')); // 25 m / s
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console.log();
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// convert a unit to a number
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// A second parameter with the unit for the exported number must be provided
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print(math.eval('number(5 cm, mm)')); // number, 50
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console.log();
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// simplify units
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console.log('simplify units');
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print(math.eval('100000 N / m^2')); // 100 kPa
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print(math.eval('9.81 m/s^2 * 100 kg * 40 m')); // 39.24 kJ
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console.log();
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// example engineering calculations
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console.log('compute molar volume of ideal gas at 65 Fahrenheit, 14.7 psi in L/mol');
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var Rg = math.unit('8.314 N m / (mol K)');
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var T = math.unit('65 degF');
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var P = math.unit('14.7 psi');
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var v = math.divide(math.multiply(Rg, T), P);
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console.log('gas constant (Rg) = ', format(Rg));
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console.log('P = ' + format(P));
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console.log('T = ' + format(T));
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console.log('v = Rg * T / P = ' + format(math.to(v, 'L/mol'))); // 23.910... L / mol
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console.log();
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console.log('compute speed of fluid flowing out of hole in a container');
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var g = math.unit('9.81 m / s^2');
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var h = math.unit('1 m');
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var v = math.pow(math.multiply(2, math.multiply(g, h)), 0.5); // Can also use math.sqrt
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console.log('g = ' + format(g));
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console.log('h = ' + format(h));
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console.log('v = (2 g h) ^ 0.5 = ' + format(v)); // 4.429... m / s
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console.log();
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console.log('electrical power consumption:');
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var expr = '460 V * 20 A * 30 days to kWh';
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console.log(expr + ' = ' + math.eval(expr)); // 6624 kWh
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console.log();
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console.log('circuit design:');
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var expr = '24 V / (6 mA)';
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console.log(expr + ' = ' + math.eval(expr)); // 4 kohm
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console.log();
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console.log('operations on arrays:');
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var B = math.eval('[1, 0, 0] T');
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var v = math.eval('[0, 1, 0] m/s');
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var q = math.eval('1 C');
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var F = math.multiply(q, math.cross(v, B));
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console.log('B (magnetic field strength) = ' + format(B)); // [1 T, 0 T, 0 T]
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console.log('v (particle velocity) = ' + format(v)); // [0 m / s, 1 m / s, 0 m / s]
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console.log('q (particle charge) = ' + format(q)); // 1 C
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console.log('F (force) = q (v cross B) = ' + format(F)); // [0 N, 0 N, -1 N]
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/**
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* Helper function to output a value in the console. Value will be formatted.
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* @param {*} value
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*/
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function print (value) {
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console.log(format(value));
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}
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/**
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* Helper function to format an output a value.
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* @param {*} value
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* @return {string} Returns the formatted value
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*/
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function format (value) {
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var precision = 14;
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return math.format(value, precision);
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}
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