1 files changed, 83 insertions, 0 deletions
diff --git a/src/c/signalProcessing/transforms/idct/didcta.c b/src/c/signalProcessing/transforms/idct/didcta.c
new file mode 100644
index 0000000..5f47516
--- /dev/null
+++ b/src/c/signalProcessing/transforms/idct/didcta.c
@@ -0,0 +1,83 @@
+/* Copyright (C) 2016 - IIT Bombay - FOSSEE
+
+ This file must be used under the terms of the CeCILL.
+ This source file is licensed as described in the file COPYING, which
+ you should have received as part of this distribution.  The terms
+ are also available at
+ http://www.cecill.info/licences/Licence_CeCILL_V2-en.txt
+ Author: Ukasha Noor
+ Organization: FOSSEE, IIT Bombay
+ Email: toolbox@scilab.in
+*/
+
+
+#include "idct.h"
+/*#include <fftw3.h>*/
+#include <math.h>
+
+void didcta(double *in,int row,int col,double *out)
+{
+	int i,j,k,u,v;
+	int n=col;
+	int x,y;
+	double res,ress;
+	double re,z,q,m;
+	if(row==1)
+	{
+		res=1./sqrt(n);
+		ress=sqrt(2./n);
+		for(u=0;u<row;u++)
+		{
+			for(v=0;v<col;v++)
+			{
+				x=v*row+u;
+				out[x]=0;
+				for(i=0;i<row;i++)
+				{
+					for(j=0;j<col;j++)
+					{
+						y=row*j+i;		
+						if(y==0)
+						out[x]+=res*in[y]*(cos(((M_PI)*(j)*(v+1./2.))/n));
+						else
+						out[x]+=ress*in[y]*(cos(((M_PI)*(j)*(v+1./2.))/n));
+					}
+				}
+			}
+				
+		}
+	}
+	else
+	{
+		for(u=0;u<row;u++)
+		{
+			for(v=0;v<col;v++)
+			{
+				x=v*row+u;
+				out[x]=0;
+				for(i=0;i<row;i++)
+				{
+					re=0;
+					for(j=0;j<col;j++)
+					{
+						y=row*j+i;
+						m=(double)in[j*row+i];
+						z=(double)(((double)v+1.0/2.0)*(double)j);
+						q=(double)(M_PI/(double)col);	
+						m=m*(cos(q*z));
+						if(j==0)
+						re+=m/sqrt((double)col);
+						else
+						re+=m*sqrt(2./col);
+					}
+					z=(double)(((double)u+1.0/2.0)*(double)i);
+					q=(double)(M_PI/(double)row);	
+					if(i==0)
+					out[x]+=(re*(cos(z*q)))/sqrt((double)row);
+					else
+					out[x]+=(re*(cos(z*q))*sqrt(2./row));
+				}
+			}
+		}
+	}					
+}