plot bar graph handling floating point values (#855)

* handling floating point values

* removelogging

libs/core/led.ts

@@ -19,19 +19,25 @@
     //% blockId=device_plot_bar_graph block="plot bar graph of %value up to %high" icon="\uf080" blockExternalInputs=true
     //% parts="ledmatrix"
     export function plotBarGraph(value: number, high: number): void {
-        let now = input.runningTime();
+        const now = input.runningTime();
         serial.writeLine(value.toString());
         value = Math.abs(value);
 
-        if (high != 0) barGraphHigh = high;
-        else if (value > barGraphHigh || now - barGraphHighLast > 10000) {
+        // auto-scale "high" is not provided
+        if (high <= 0) {
+            barGraphHigh = high;
+        } else if (value > barGraphHigh || now - barGraphHighLast > 10000) {
             barGraphHigh = value;
             barGraphHighLast = now;
         }
 
-        barGraphHigh = Math.max(barGraphHigh, 16);
+        // normalize lack of data to 0..1 
+        if (barGraphHigh < 16 * Number.EPSILON)
+            barGraphHigh = 1;        
 
-        let v = (value * 15) / barGraphHigh;
+        // normalize value to 0..1
+        const v = value / barGraphHigh;
+        const dv = 1 / 16;
         let k = 0;
         for (let y = 4; y >= 0; --y) {
             for (let x = 0; x < 3; ++x) {
@@ -42,7 +48,7 @@
                     plot(2 - x, y);
                     plot(2 + x, y);
                 }
-                ++k;
+                k += dv;
             }
         }
     }

libs/core/math.ts

@@ -0,0 +1,16 @@
+namespace Math {
+
+    export const E = 2.718281828459045;
+    export const LN2 = 0.6931471805599453;
+    export const LN10 = 2.302585092994046;
+    export const LOG2E = 1.4426950408889634;
+    export const LOG10E = 0.4342944819032518;
+    export const PI = 3.141592653589793;
+    export const SQRT1_2 = 0.7071067811865476;
+    export const SQRT2 = 1.4142135623730951;
+
+}
+
+namespace Number {
+    export const EPSILON = 2.220446049250313e-16;
+}

libs/core/pxt.json

@@ -8,6 +8,7 @@
         "pxt.h",
         "pxtbase.h",
         "pxtcore.h",
+        "math.ts",
         "dal.d.ts",
         "enums.d.ts",
         "shims.d.ts",