zenno/doc/frbm: update with charts &c.

zenno/src/lib/prob.ts

@@ -0,0 +1,9 @@
+import * as math from "mathjs";
+
+export function binomPMF(p: number, n: number, k: number): number {
+    // Operate in log domain for precision.
+    const lc = math.lgamma(n+1) - math.lgamma(k+1) - math.lgamma(n-k+1);
+    const lpk = k * math.log(p);
+    const lr = (n - k) * math.log(1 - p);
+    return math.exp(lc + lpk + lr);
+}