From 79a083f28e9df04768151c8a916934716b4a2646 Mon Sep 17 00:00:00 2001
From: Richard Knight <q@1bpm.net>
Date: Mon, 24 Aug 2020 05:20:46 +0100
Subject: initial

---
 src/cosine.cpp | 131 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 131 insertions(+)
 create mode 100644 src/cosine.cpp

(limited to 'src/cosine.cpp')

diff --git a/src/cosine.cpp b/src/cosine.cpp
new file mode 100644
index 0000000..78cafd8
--- /dev/null
+++ b/src/cosine.cpp
@@ -0,0 +1,131 @@
+/*
+    cosine.cpp
+    Copyright (C) 2015 John Burkardt
+    Copyright (C) 2019 Richard Knight
+
+
+    This program is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Lesser General Public
+    License as published by the Free Software Foundation; either
+    version 3 of the License, or (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program; if not, write to the Free Software Foundation,
+    Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ 
+ */
+
+#include <cmath>
+#include <cstdlib>
+#include <iostream>
+#include <ctime>
+#include <plugin.h>
+
+using namespace std;
+
+#include "cosine.hpp"
+
+//****************************************************************************80
+
+void cosine_transform_data (csnd::Vector<MYFLT> d, csnd::Vector<MYFLT> c)
+
+//****************************************************************************80
+//
+//  Purpose:
+//
+//    COSINE_TRANSFORM_DATA does a cosine transform on a vector of data.
+//
+//  Licensing:
+//
+//    This code is distributed under the GNU LGPL license.
+//
+//  Modified:
+//
+//    27 August 2015
+//
+//  Author:
+//
+//    John Burkardt
+//
+//  Parameters:
+//
+//    Input, integer N, the number of data points.
+//
+//    Input, double D[N], the vector of data.
+//
+//    Output, double COSINE_TRANSFORM_DATA[N], the transform coefficients.
+//
+{
+  int n = d.len();
+  double angle;
+  int i;
+  int j;
+  const double r8_pi = 3.141592653589793;
+
+
+  for ( i = 0; i < n; i++ )
+  {
+    c[i] = 0.0;
+    for ( j = 0; j < n; j++ )
+    {
+      angle = r8_pi * ( double ) ( i * ( 2 * j + 1 ) ) / ( double ) ( 2 * n );
+      c[i] = c[i] + cos ( angle ) * d[j];
+    }
+    c[i] = c[i] * sqrt ( 2.0 / ( double ) ( n ) );
+  }
+}
+//****************************************************************************80
+
+void cosine_transform_inverse (csnd::Vector<MYFLT> c, csnd::Vector<MYFLT> d)
+
+//****************************************************************************80
+//
+//  Purpose:
+//
+//    COSINE_TRANSFORM_INVERSE does an inverse cosine transform.
+//
+//  Licensing:
+//
+//    This code is distributed under the GNU LGPL license.
+//
+//  Modified:
+//
+//    27 August 2015
+//
+//  Author:
+//
+//    John Burkardt
+//
+//  Parameters:
+//
+//    Input, integer N, the number of data points.
+//
+//    Input, double C[N], the vector of transform coefficients
+//
+//    Output, double COSINE_TRANSFORM_INVERSE[N], the original data.
+//
+{
+  int n = c.len();
+  double angle;
+  int i;
+  int j;
+  double r8_pi = 3.141592653589793;
+
+
+  for ( i = 0; i < n; i++ )
+  {
+    d[i] = c[0] / 2.0;
+    for ( j = 1; j < n; j++ )
+    {
+      angle = r8_pi * ( double ) ( ( 2 * i + 1 ) * j ) / ( double ) ( 2 * n );
+      d[i] = d[i] + cos ( angle ) * c[j];
+    }
+    d[i] = d[i] * sqrt ( 2.0 / ( double ) ( n ) );
+  }
+}
+//****************************************************************************80
-- 
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