matfra/lr filter

## lr filter
<!DOCTYPE html>
<html>
	<head>
		<title>Linkwitz-Riley filter calculator</title>
	</head>

	<body>
		<p id="demo"></p>
<script>
var PI = 3.141592653589793
var AVAILABLE_CAPACITORS=[3.3e-9];

var AVAILABLE_RESISTORS=[
     1, 2.2, 4.7, 5.6,
     7.5, 8.2, 10, 15,
     22, 27, 33, 39,
     47, 56, 68, 75,
     82, 100, 120, 150,
     180, 220, 270, 330,
     390, 470, 510, 680,
     820, 1000, 1500, 2200,
     3000, 3900, 4700, 5600,
     6800, 7500, 8200, 10000,
     15000, 22000, 33000, 39000,
     47000, 56000, 68000, 75000,
     82000, 100000, 150000, 180000,
     220000, 330000, 470000, 560000,
     680000, 1000000, 1500000, 2000000,
     3300000, 4700000, 5600000, 10000000 ];


	function parallel(a, b, component) {
		switch (component) {
			case 'r':
				return ( a * b ) / ( a + b );
				break;
			case 'c':
				return a + b;
				break;
			}
		}

	function series(a, b, component) {
		switch (component) {
			case 'r':
				return a + b;
			case 'c':
				return ( a * b ) / ( a + b );
			}
		}

	function compare(value, target, precision) {
		return Math.abs ( 1 - ( value / target ) ) < precision
	}

	function list_combo(stock, component) {
		result = []
		 for (i = 0; i < stock.length; i++) {
		 	result = result.concat([stock[i]]);
    	for (j = 0; j < stock.length; j++) {
        result = result.concat(series(stock[i], stock[j], component));
			  result = result.concat(parallel(stock[i], stock[j], component));
			}
		}
		return result
	}

	function find_combo(target, stock, component, precision) {
		result=[]
		 for (i = 0; i < stock.length; i++) {
		 	if ( compare(stock[i], target, precision) ) {
		 		result = result.concat([stock[i]]);
		 	} else {
    		for (j = 0; j < stock.length; j++) {
    			if (compare(
    			series(stock[i], stock[j], component),
    			target,
    			precision)) {
            result = result.concat([stock[i] + ' -- ' + stock[j]]);
        	}
          if (compare(
					parallel(stock[i], stock[j], component),
					target,
					precision)) {
					  result = result.concat([stock[i] + ' // ' + stock[j]]);
					}
				}
		 	}
		}
		return result
	}

	function get_freq(r,c) {
		return 1 / ( 2.83 * PI * c * r)
	}

	function get_r(f,c) {
		return 1 / ( 2.83 * PI * c * f)
	}

	function list_freq(r_stock, c_stock) {
		r = list_combo(r_stock, 'r');
		c = list_combo(c_stock, 'c');
		frequencies = [];
		for (i = 0; i < r.length; i++) {
			for (j = 0; j < c.length; j++) {
				 frequencies = frequencies.concat([get_freq(r[i],c[j])]);
			}
		}
		return frequencies
	}

	function get_best_freq(f_target, r_stock, c_stock) {
		frequencies = list_freq(r_stock, c_stock);
		best_match = 0;
		for (i = 0; i < frequencies.length; i++) {
			if (Math.abs(f_target - best_match) > Math.abs(f_target - frequencies[i])) {
				best_match = frequencies[i];
			}
		}
		return best_match
	}

// TO-DO: get freq for every combination of c and r
// Get closest frequency with combination
	function getQueryParams(qs) {
    	qs = qs.split('+').join(' ');

    	var params = {},
    	    tokens,
    	    re = /[?&]?([^=]+)=([^&]*)/g;

    	while (tokens = re.exec(qs)) {
    	    params[decodeURIComponent(tokens[1])] = decodeURIComponent(tokens[2]);
    	}

    		return params;
	}

	var query = getQueryParams(document.location.search);

	document.getElementById("demo").innerHTML = get_best_freq( query.freq, AVAILABLE_RESISTORS, AVAILABLE_CAPACITORS);


</script>

<form action="Linkwitz-Riley.html">
Cutoff Frequency: <input type="text" name="freq" value="2400"><br>
<input type="submit" value="Submit">
</form>

	</body>
</html>
	<!DOCTYPE html>
	<html>
	<head>
	<title>Linkwitz-Riley filter calculator</title>
	</head>

	<body>
	<p id="demo"></p>
	<script>
	var PI = 3.141592653589793
	var AVAILABLE_CAPACITORS=[3.3e-9];

	var AVAILABLE_RESISTORS=[
	1, 2.2, 4.7, 5.6,
	7.5, 8.2, 10, 15,
	22, 27, 33, 39,
	47, 56, 68, 75,
	82, 100, 120, 150,
	180, 220, 270, 330,
	390, 470, 510, 680,
	820, 1000, 1500, 2200,
	3000, 3900, 4700, 5600,
	6800, 7500, 8200, 10000,
	15000, 22000, 33000, 39000,
	47000, 56000, 68000, 75000,
	82000, 100000, 150000, 180000,
	220000, 330000, 470000, 560000,
	680000, 1000000, 1500000, 2000000,
	3300000, 4700000, 5600000, 10000000 ];


	function parallel(a, b, component) {
	switch (component) {
	case 'r':
	return ( a * b ) / ( a + b );
	break;
	case 'c':
	return a + b;
	break;
	}
	}

	function series(a, b, component) {
	switch (component) {
	case 'r':
	return a + b;
	case 'c':
	return ( a * b ) / ( a + b );
	}
	}

	function compare(value, target, precision) {
	return Math.abs ( 1 - ( value / target ) ) < precision
	}

	function list_combo(stock, component) {
	result = []
	for (i = 0; i < stock.length; i++) {
	result = result.concat([stock[i]]);
	for (j = 0; j < stock.length; j++) {
	result = result.concat(series(stock[i], stock[j], component));
	result = result.concat(parallel(stock[i], stock[j], component));
	}
	}
	return result
	}

	function find_combo(target, stock, component, precision) {
	result=[]
	for (i = 0; i < stock.length; i++) {
	if ( compare(stock[i], target, precision) ) {
	result = result.concat([stock[i]]);
	} else {
	for (j = 0; j < stock.length; j++) {
	if (compare(
	series(stock[i], stock[j], component),
	target,
	precision)) {
	result = result.concat([stock[i] + ' -- ' + stock[j]]);
	}
	if (compare(
	parallel(stock[i], stock[j], component),
	target,
	precision)) {
	result = result.concat([stock[i] + ' // ' + stock[j]]);
	}
	}
	}
	}
	return result
	}

	function get_freq(r,c) {
	return 1 / ( 2.83 * PI * c * r)
	}

	function get_r(f,c) {
	return 1 / ( 2.83 * PI * c * f)
	}

	function list_freq(r_stock, c_stock) {
	r = list_combo(r_stock, 'r');
	c = list_combo(c_stock, 'c');
	frequencies = [];
	for (i = 0; i < r.length; i++) {
	for (j = 0; j < c.length; j++) {
	frequencies = frequencies.concat([get_freq(r[i],c[j])]);
	}
	}
	return frequencies
	}

	function get_best_freq(f_target, r_stock, c_stock) {
	frequencies = list_freq(r_stock, c_stock);
	best_match = 0;
	for (i = 0; i < frequencies.length; i++) {
	if (Math.abs(f_target - best_match) > Math.abs(f_target - frequencies[i])) {
	best_match = frequencies[i];
	}
	}
	return best_match
	}

	// TO-DO: get freq for every combination of c and r
	// Get closest frequency with combination
	function getQueryParams(qs) {
	qs = qs.split('+').join(' ');

	var params = {},
	tokens,
	re = /[?&]?([^=]+)=([^&]*)/g;

	while (tokens = re.exec(qs)) {
	params[decodeURIComponent(tokens[1])] = decodeURIComponent(tokens[2]);
	}

	return params;
	}

	var query = getQueryParams(document.location.search);

	document.getElementById("demo").innerHTML = get_best_freq( query.freq, AVAILABLE_RESISTORS, AVAILABLE_CAPACITORS);



	</script>

	<form action="Linkwitz-Riley.html">
	Cutoff Frequency: <input type="text" name="freq" value="2400"><br>
	<input type="submit" value="Submit">
	</form>

	</body>
	</html>