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opendsp · Nov 9, 2014 · 17f7f88 · 17f7f88
commit 17f7f88
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diff --git a/index.js b/index.js
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+
+/**
+ * @module prewarp
+ * @author stagas
+ * @org opendsp
+ * @license mit
+ */
+
+export default function prewarp(f){
+  return Math.tan(Math.PI * f / sampleRate);
+}
diff --git a/test.js b/test.js
@@ -0,0 +1,27 @@
+
+/**
+ * test
+ */
+
+import debug from 'debug';
+import prewarp from './index';
+
+var out = 0;
+
+var w = prewarp(0);
+var a = w / (1 + w);
+out += a.toFixed(1)==='0.0';
+
+var w = prewarp(sampleRate/4);
+var a = w / (1 + w);
+out += a.toFixed(1)==='0.5';
+
+var w = prewarp(sampleRate/2);
+var a = w / (1 + w);
+out += a.toFixed(1)==='1.0';
+
+debug(3 === out && 'all tests pass');
+
+export function dsp(t){
+  return 0;
+}