115 lines
3.6 KiB
JavaScript
115 lines
3.6 KiB
JavaScript
import { factory } from '../../utils/factory.js';
|
|
var name = 'freqz';
|
|
var dependencies = ['typed', 'add', 'multiply', 'Complex', 'divide', 'matrix'];
|
|
export var createFreqz = /* #__PURE__ */factory(name, dependencies, _ref => {
|
|
var {
|
|
typed,
|
|
add,
|
|
multiply,
|
|
Complex,
|
|
divide,
|
|
matrix
|
|
} = _ref;
|
|
/**
|
|
* Calculates the frequency response of a filter given its numerator and denominator coefficients.
|
|
*
|
|
* Syntax:
|
|
* math.freqz(b, a)
|
|
* math.freqz(b, a, w)
|
|
*
|
|
* Examples:
|
|
* math.freqz([1, 2], [1, 2, 3], 4) // returns { h: [0.5 + 0i, 0.4768589245763655 + 0.2861153547458193i, 0.25000000000000006 + 0.75i, -0.770976571635189 + 0.4625859429811135i], w: [0, 0.7853981633974483, 1.5707963267948966, 2.356194490192345 ] }
|
|
* math.freqz([1, 2], [1, 2, 3], [0, 1]) // returns { h: [0.5 + 0i, 0.45436781 + 0.38598051i], w: [0, 1] }
|
|
*
|
|
* See also:
|
|
* zpk2tf
|
|
*
|
|
* @param {Array.<number>} b The numerator coefficients of the filter.
|
|
* @param {Array.<number>} a The denominator coefficients of the filter.
|
|
* @param {Array.<number>} [w] A vector of frequencies (in radians/sample) at which the frequency response is to be computed or the number of points to compute (if a number is not provided, the default is 512 points)
|
|
* @returns {Object} An object with two properties: h, a vector containing the complex frequency response, and w, a vector containing the normalized frequencies (in radians/sample) at which the response was computed.
|
|
*
|
|
*
|
|
*/
|
|
return typed(name, {
|
|
'Array, Array': function Array_Array(b, a) {
|
|
var w = createBins(512);
|
|
return _freqz(b, a, w);
|
|
},
|
|
'Array, Array, Array': function Array_Array_Array(b, a, w) {
|
|
return _freqz(b, a, w);
|
|
},
|
|
'Array, Array, number': function Array_Array_number(b, a, w) {
|
|
if (w < 0) {
|
|
throw new Error('w must be a positive number');
|
|
}
|
|
var w2 = createBins(w);
|
|
return _freqz(b, a, w2);
|
|
},
|
|
'Matrix, Matrix': function Matrix_Matrix(b, a) {
|
|
// console.log('here')
|
|
var _w = createBins(512);
|
|
var {
|
|
w,
|
|
h
|
|
} = _freqz(b.valueOf(), a.valueOf(), _w);
|
|
return {
|
|
w: matrix(w),
|
|
h: matrix(h)
|
|
};
|
|
},
|
|
'Matrix, Matrix, Matrix': function Matrix_Matrix_Matrix(b, a, w) {
|
|
var {
|
|
h
|
|
} = _freqz(b.valueOf(), a.valueOf(), w.valueOf());
|
|
return {
|
|
h: matrix(h),
|
|
w: matrix(w)
|
|
};
|
|
},
|
|
'Matrix, Matrix, number': function Matrix_Matrix_number(b, a, w) {
|
|
if (w < 0) {
|
|
throw new Error('w must be a positive number');
|
|
}
|
|
var _w = createBins(w);
|
|
var {
|
|
h
|
|
} = _freqz(b.valueOf(), a.valueOf(), _w);
|
|
return {
|
|
h: matrix(h),
|
|
w: matrix(_w)
|
|
};
|
|
}
|
|
});
|
|
function _freqz(b, a, w) {
|
|
var num = [];
|
|
var den = [];
|
|
for (var i = 0; i < w.length; i++) {
|
|
var sumNum = Complex(0, 0);
|
|
var sumDen = Complex(0, 0);
|
|
for (var j = 0; j < b.length; j++) {
|
|
sumNum = add(sumNum, multiply(b[j], Complex(Math.cos(-j * w[i]), Math.sin(-j * w[i]))));
|
|
}
|
|
for (var _j = 0; _j < a.length; _j++) {
|
|
sumDen = add(sumDen, multiply(a[_j], Complex(Math.cos(-_j * w[i]), Math.sin(-_j * w[i]))));
|
|
}
|
|
num.push(sumNum);
|
|
den.push(sumDen);
|
|
}
|
|
var h = [];
|
|
for (var _i = 0; _i < num.length; _i++) {
|
|
h.push(divide(num[_i], den[_i]));
|
|
}
|
|
return {
|
|
h,
|
|
w
|
|
};
|
|
}
|
|
function createBins(n) {
|
|
var bins = [];
|
|
for (var i = 0; i < n; i++) {
|
|
bins.push(i / n * Math.PI);
|
|
}
|
|
return bins;
|
|
}
|
|
}); |