// test atan
var assert = require('assert'),
    math = require('../../../index.js'),
    approx = require('../../../tools/approx.js'),
    pi = math.pi,
    complex = math.complex,
    matrix = math.matrix,
    unit = math.unit,
    atan = math.atan,
    tan = math.tan;

// number
approx.equal(atan(-1) / pi, -0.25);
approx.equal(atan(-0.5) / pi, -0.147583617650433);
approx.equal(atan(0) / pi, 0);
approx.equal(atan(0.5) / pi, 0.147583617650433);
approx.equal(atan(1) / pi, 0.25);

// complex
var re = 1.409921049596575,
    im = 0.229072682968539;
approx.deepEqual(atan(complex('2+3i')), complex(re, im));
approx.deepEqual(atan(complex('2-3i')), complex(re, -im));
approx.deepEqual(atan(complex('-2+3i')), complex(-re, im));
approx.deepEqual(atan(complex('-2-3i')), complex(-re, -im));
approx.deepEqual(atan(complex('i')), complex(NaN, NaN)); // TODO: should return NaN + Infi instead
approx.deepEqual(atan(complex('1')), 0.785398163397448);
approx.deepEqual(atan(complex('1+i')), complex(1.017221967897851, 0.402359478108525));

// unit
assert.throws(function () {atan(unit('45deg'))});
assert.throws(function () {atan(unit('5 celsius'))});

// string
assert.throws(function () {atan('string')});

// inverse
approx.equal(atan(tan(-1)), -1);
approx.equal(atan(tan(0)), 0);
approx.equal(atan(tan(0.1)), 0.1);
approx.equal(atan(tan(0.5)), 0.5);
approx.equal(atan(tan(2)), -1.14159265358979);

// matrix, array, range
var atan123 = [0.785398163397448, 1.107148717794090, 1.249045772398254];
approx.deepEqual(atan([1,2,3]), atan123);
approx.deepEqual(atan(math.range('1:4')), atan123);
approx.deepEqual(atan(matrix([1,2,3])), matrix(atan123));