diff carfac/carfac_util.cc @ 643:8b70f4cf00c7

Additional changes to C++ CARFAC on the basis of ronw's comments on r289. Moved CARFAC::Design to CARFAC::CARFAC and CARFAC::Reset(), moved carfac_common.h to common.h, CARFACDetect to carfac_util.h/cc, FloatArray and Float2dArray to ArrayX and ArrayXX, improved variable naming, made a start on improved commenting documentation.

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/carfac/carfac_util.cc	Tue Jun 04 18:30:22 2013 +0000
@@ -0,0 +1,35 @@
+//
+//  carfac_util.cc
+//  CARFAC Open Source C++ Library
+//
+//  Created by Alex Brandmeyer on 6/3/13.
+//
+// This C++ file is part of an implementation of Lyon's cochlear model:
+// "Cascade of Asymmetric Resonators with Fast-Acting Compression"
+// to supplement Lyon's upcoming book "Human and Machine Hearing"
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "carfac_util.h"
+
+ArrayX CARFACDetect (const ArrayX& x) {
+  ArrayX conductance, z, set;
+  FPType a = 0.175;
+  // This offsets the low-end tail into negative x territory.
+  // The parameter is adjusted for the book, to make the 20% DC response
+  // threshold at 0.1.
+  z  = x + a;
+  // Zero is the final answer for many points.
+  conductance = (z < 0).select(0.0, (z*z*z) / (z*z*z + z*z + 0.1));
+  return conductance;
+}
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