Merge branch 'master' of leafbla.de:dominic/ResistorJS

README.md

@@ -3,18 +3,29 @@ ResistorJS is a Javascript library intended to compose electronical resistors.
 
 ## Using Resistors in Code
 In order to instantiate an 100 Ohm resistor, we simply call `new Resistor(100)`. In order to compose several resistors, the composite resistor types `SeriesResistor` and `ParallelResistor` are available.
-```
+```JS
 var r1 = new Resistor(100);
 var r2 = new Resistor(150);
 // Combining resistors
 var inSeries = r1.series(r2); // type: SeriesResistor
 var inParallel = r1.parallel(r2); // type: ParallelResistor
 
+// Computing resulting resistors
+inSeries.getOhmage() // 250
+inParallel.getOhmage() // 60
+
 // Drawing to DOM
 r1.draw(div1);
 r2.draw(div2);
 inSeries.draw(div3);
 inParallel.draw(div4);
 ```
-Calling `Resistor.draw(element)` generates an SVG from the constructed Resistor object. Above code would render something like this:
+Calling `Resistor.draw(element)` generates an SVG from the constructed Resistor object. Above code will render something like this:
 ![Your browser cannot display images :(](imgs/tutorial.png)
+
+## Computing approximations
+Sometimes, one wants to use ohmages in an electronical circuit that simply are not available. By cleverly combining a sufficient number of available resistors, one can approximate the needed values. For instance, using only 100Ohm and 100Ohm resistors, one can construct a (sufficiently close to) 127Ohm resistor like so:
+
+![Your browser can still not display images :(](imgs/127ohm.png)
+
+`main.js` contains an example application using dynamic programming that computes sufficiently good approximations for resistor values within a set range.

main.js

@@ -1,5 +1,9 @@
 import { Resistor, SeriesResistor, ParallelResistor } from './modules/resistors.js';
 
+window.Resistor = Resistor
+window.SeriesResistor = SeriesResistor
+window.ParallelResistor = ParallelResistor
+
 var resistorValues = [100, 1000]
 var N = 4
 var maxValue = Math.max(...resistorValues)
@@ -41,6 +45,7 @@ console.log(`Parameters: N = ${N}, values = ${resistorValues} `);
 for (i = 0; i < N; i++)
     bottomUpDP();
 console.log("Finished computation of DP array");
+window.numberline = numberline
 
 function missings() {
     var missing = new Set()
@@ -52,6 +57,3 @@ function missings() {
 }
 console.log(`We found a composite resistor for every value in the range [1, ${N * maxValue + 1}] but for: ${[...missings()].join(",")}`)
 
-numberline[420].draw() // Draw the Resistor diagram for 420 Ohm as SVG
-
-console.log(numberline)

modules/resistors.js

@@ -35,7 +35,7 @@ class Resistor {
         var [width, height] = [50, 100]
         return [svg, width, height]
     }
-    draw() {
+    draw(element = document.getElementsByTagName("body")[0]) {
         var [svg, width, height] = this.getSVG();
         var maxHeight = height + 2*25
         var maxWidth = width
@@ -47,7 +47,7 @@ class Resistor {
             ${svg}
             </g>
             </svg>`
-        document.getElementsByTagName("body")[0].innerHTML = thesvg;
+        element.innerHTML = thesvg;
     }
 }
 
@@ -57,7 +57,7 @@ class NestedResistor extends Resistor {
     constructor(l, func, instance) {
         super(func(l.map(e => e.getOhmage())));
         this.func = func
-        this.children = flatten(l, instance.constructor.name);
+        this.children = flatten(l, instance);
     }
     cost() {
         return sum(this.children.map(e => e.cost()));