-
Notifications
You must be signed in to change notification settings - Fork 1
/
jquery.fft.js
178 lines (162 loc) · 4.71 KB
/
jquery.fft.js
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
/*!
* jQuery FFT Plugin v1.0.3
* This code is javascript converted version of following VBA source:
* Tetsuya Kawamura 川村 哲也,
* エンジニアのためのExcelナビシリーズ 数値計算入門, page 194, (2012)
* ISBN 987-4-9011092-81-4
*
* Copyright 2017 Hideto Manjo
* Released under the MIT license
*/
/*jslint
bitwise, node, browser, for, this
*/
/*global
define
*/
;
(function (root, factory) {
"use strict";
if (typeof define === "function" && define.amd) {
define(factory);
} else if (typeof exports === "object") {
module.exports = factory();
} else {
root.FFT = factory();
}
}(this, function () {
"use strict";
var FFT = function FFT(settings) {
this.settings = settings || {samplingrate: 1};
};
FFT.prototype = {
dim: function dim(F1, F2) {
var N = F1.length;
//limited 2^x
while (true) {
if (!(N & (N - 1))) {
break;
}
N = N + 1;
F1.push(0);
F2.push(0);
}
return N;
},
loop: function loop(N, callback) {
var m = N / 2;
var ans = [];
var i;
for (i = 0; i < m; i = i + 1) {
ans.push(callback.call(null, i));
}
return ans;
},
amplitude: function amplitude(F1, F2) {
return this.loop(this.dim(F1, F2), function (i) {
return Math.sqrt(F1[i] * F1[i] + F2[i] * F2[i]);
});
},
power: function power(F1, F2) {
return this.loop(this.dim(F1, F2), function (i) {
return F1[i] * F1[i] + F2[i] * F2[i];
});
},
phase: function phase(F1, F2) {
return this.loop(this.dim(F1, F2), function (i) {
return Math.atan2(F2[i], F1[i]);
});
},
frequencies: function frequencies(F1, F2, samplingrate) {
var sps = samplingrate || this.settings.samplingrate;
var N = this.dim(F1, F2);
return this.loop(N, function (i) {
return sps * (i) / N;
});
},
periods: function periods(F1, F2, samplingrate) {
var sps = samplingrate || this.settings.samplingrate;
var N = this.dim(F1, F2);
return this.loop(N, function (i) {
return N / (sps * (i));
});
},
calc: function calc(SW, F1, F2) {
var N = this.dim(F1, F2);
var WN = 2 * Math.PI / N;
var INDEX = Math.log2(N);
var DX = 1 / N;
var m = N;
var A1;
var A2;
var B1;
var B2;
var W1;
var W2;
var C;
var S;
var T;
var i;
var j;
var k;
var l;
var jl;
var jm;
var m1;
var kl;
for (l = 0; l < INDEX; l = l + 1) {
T = 0;
m1 = m;
m = m / 2;
for (k = 0; k < m; k = k + 1) {
kl = k - m1;
C = Math.cos(T);
S = -SW * Math.sin(T);
T = T + WN;
for (j = m1; j < N + 1; j = j + m1) {
jl = j + kl;
jm = jl + m;
A1 = F1[jl];
A2 = F1[jm];
B1 = F2[jl];
B2 = F2[jm];
F1[jl] = A1 + A2;
F2[jl] = B1 + B2;
F1[jm] = (A1 - A2) * C + (B1 - B2) * S;
F2[jm] = (B1 - B2) * C - (A1 - A2) * S;
}
}
WN = 2 * WN;
}
j = 0;
for (i = 0; i < N - 1; i = i + 1) {
if (i < j) {
W1 = F1[j];
W2 = F2[j];
F1[j] = F1[i];
F2[j] = F2[i];
F1[i] = W1;
F2[i] = W2;
}
k = N / 2;
while (true) {
if (k > j) {
break;
}
j = j - k;
k = k / 2;
}
j = j + k;
}
if (SW < 0) {
for (i = 0; i < N; i = i + 1) {
F1[i] = DX * F1[i];
F2[i] = DX * F2[i];
}
}
return [F1, F2];
}
};
// export
return FFT;
}));