A-M baby

Task/Map-range/Go/map-range-1.go

@@ -0,0 +1,19 @@
+package main
+
+import "fmt"
+
+type rangeBounds struct {
+    b1, b2 float64
+}
+
+func mapRange(x, y rangeBounds, n float64) float64 {
+    return y.b1 + (n - x.b1) * (y.b2 - y.b1) / (x.b2 - x.b1)
+}
+
+func main() {
+    r1 := rangeBounds{0, 10}
+    r2 := rangeBounds{-1, 0}
+    for n := float64(0); n <= 10; n += 2 {
+        fmt.Println(n, "maps to", mapRange(r1, r2, n))
+    }
+}

Task/Map-range/Go/map-range-2.go

@@ -0,0 +1,37 @@
+package main
+
+import "fmt"
+
+type rangeBounds struct {
+    b1, b2 float64
+}
+
+func newRangeMap(xr, yr rangeBounds) func(float64) (float64, bool) {
+    // normalize direction of ranges so that out-of-range test works
+    if xr.b1 > xr.b2 {
+        xr.b1, xr.b2 = xr.b2, xr.b1
+        yr.b1, yr.b2 = yr.b2, yr.b1
+    }
+    // compute slope, intercept
+    m := (yr.b2 - yr.b1) / (xr.b2 - xr.b1)
+    b := yr.b1 - m*xr.b1
+    // return function literal
+    return func(x float64) (y float64, ok bool) {
+        if x < xr.b1 || x > xr.b2 {
+            return 0, false // out of range
+        }
+        return m*x + b, true
+    }
+}
+
+func main() {
+    rm := newRangeMap(rangeBounds{0, 10}, rangeBounds{-1, 0})
+    for s := float64(-2); s <= 12; s += 2 {
+        t, ok := rm(s)
+        if ok {
+            fmt.Printf("s: %5.2f  t: %5.2f\n", s, t)
+        } else {
+            fmt.Printf("s: %5.2f  out of range\n", s)
+        }
+    }
+}