From: Scott Worley <scottworley@scottworley.com>
Date: Fri, 24 May 2019 15:04:04 +0000 (-0700)
Subject: Loose equality comparisons for floats
X-Git-Tag: v1.0
X-Git-Url: http://git.scottworley.com/inverse-tax/commitdiff_plain/refs/tags/v1.0

Loose equality comparisons for floats
---

diff --git a/tax.js b/tax.js
index 2687387..10c44f3 100644
--- a/tax.js
+++ b/tax.js
@@ -1,5 +1,13 @@
 "use strict";
 
+function near(a, b, epsilon = 1e-6) {
+  return Math.abs(a - b) < epsilon;
+}
+
+function less_than_or_near(a, b, epsilon = 1e-6) {
+  return a < b || near(a, b, epsilon);
+}
+
 function parse_table(as_text) {
   function parse_line(line) {
     return line.trim().split(' ').filter(x => x !== '').map(x => parseFloat(x));
@@ -83,7 +91,7 @@ function invert(table) {
   });
   return function(net) {
     for (const [start, end, m, b] of inverse_table) {
-      if (start <= net && net <= end) {
+      if (less_than_or_near(start, net) && less_than_or_near(net, end)) {
         return (net - b) / m;
       }
     }
diff --git a/tax.test.js b/tax.test.js
index 29f436f..5080001 100644
--- a/tax.test.js
+++ b/tax.test.js
@@ -6,10 +6,6 @@ function test(description, f) {
   f();
 }
 
-function near(a, b, epsilon = 1e-6) {
-  return Math.abs(a - b) < epsilon;
-}
-
 function rand(limit = 99) {
   return Math.round(Math.random() * limit);
 }