mirror of
https://github.com/josdejong/mathjs.git
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134 lines
3.6 KiB
JavaScript
134 lines
3.6 KiB
JavaScript
var assert = require('assert'),
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error = require('../../../lib/error/index'),
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approx = require('../../../tools/approx'),
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math = require('../../../index');
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describe('det', function() {
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it('should calculate correctly the determinant of a NxN matrix', function() {
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assert.equal(math.det([5]), 5);
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assert.equal(math.det([[1,2],[3,4]]), -2);
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assert.equal(math.det(math.matrix([[1,2],[3,4]])), -2);
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approx.equal(math.det([
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[-2, 2, 3],
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[-1, 1, 3],
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[ 2, 0, -1]
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]), 6);
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approx.equal(math.det([
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[ 1, 4, 7],
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[ 3, 0, 5],
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[-1, 9, 11]
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]), -8);
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approx.equal(math.det([
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[1,7,4,3,7],
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[0,7,0,3,7],
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[0,7,4,3,0],
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[1,7,5,9,7],
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[2,7,4,3,7]
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]), -1176);
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approx.equal(math.det(math.diag([4,-5,6])), -120);
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});
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it('should return 1 for the identity matrix',function() {
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assert.equal(math.det(math.eye(7)), 1);
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assert.equal(math.det(math.eye(2)), 1);
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assert.equal(math.det(math.eye(1)), 1);
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});
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it('should return 0 for a singular matrix',function() {
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assert.equal(math.det([
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[1, 0],
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[0, 0]
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]), 0);
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assert.equal(math.det([
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[1, 0],
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[1, 0]
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]), 0);
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assert.equal(math.det([
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[2, 6],
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[1, 3]
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]), 0);
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assert.equal(math.det([
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[1, 0, 0],
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[0, 0, 0],
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[1, 0, 0]
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]), 0);
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});
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it('should calculate the determinant for a scalar',function() {
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assert.equal(math.det(7), 7);
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var c1 = math.complex(2, 3);
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var c2 = math.det(c1);
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assert.deepEqual(c1, c2);
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// c2 should be a clone
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c1.re = 0;
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assert.equal(c1.re, 0);
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assert.equal(c2.re, 2);
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});
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it('should calculate the determinant for a 1x1 matrix',function() {
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var c1 = math.complex(2, 3);
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var c2 = math.det([[c1]]);
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assert.deepEqual(c1, c2);
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// c2 should be a clone
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c1.re = 0;
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assert.equal(c1.re, 0);
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assert.equal(c2.re, 2);
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});
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it('should calculate correctly the determinant of a matrix with bignumbers', function() {
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var bignumber = math.bignumber;
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// 1x1
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assert.deepEqual(math.det([bignumber(5)]), bignumber(5));
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// 2x2
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assert.deepEqual(math.det([
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[bignumber(1), bignumber(2)],
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[bignumber(3), bignumber(4)]
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]), bignumber(-2));
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// 3x3
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assert.deepEqual(math.det([
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[bignumber(-2), bignumber(2), bignumber( 3)],
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[bignumber(-1), bignumber(1), bignumber( 3)],
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[bignumber( 2), bignumber(0), bignumber(-1)]
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]), bignumber(6));
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// the following would fail with regular Numbers due to a precision overflow
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assert.deepEqual(math.det([
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[bignumber(1e10+1), bignumber(1e10)],
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[bignumber(1e10), bignumber(1e10-1)]
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]), bignumber(-1));
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});
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it('should calculate the determinant of a matrix with mixed numbers and bignumbers', function() {
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var bignumber = math.bignumber;
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assert.deepEqual(math.det([
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[1, bignumber(2)],
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[bignumber(3), 4]
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]), bignumber(-2));
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});
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it('should not change the value of the initial matrix', function() {
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var m_test = [[1,2,3],[4,5,6],[7,8,9]];
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math.det(m_test);
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assert.deepEqual(m_test, [[1,2,3],[4,5,6],[7,8,9]]);
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});
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it('should not accept a non-square matrix', function() {
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assert.throws(function() { math.det([1,2]); });
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assert.throws(function() { math.det([[1,2,3],[1,2,3]]); });
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assert.throws(function() { math.det([0,1],[0,1],[0,1]); });
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});
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it('should not accept arrays with dimensions higher than 2', function() {
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assert.throws(function() { math.det([[[1]]]); }, RangeError);
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assert.throws(function() { math.det(math.matrix([[[1]]])); }, RangeError);
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});
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}); |