added functions which computes variances , the float complex functions seems to have a weak precision ( 1-e04 instead of 1-e06 for some value )

1 files changed, 50 insertions, 0 deletions

diff --git a/src/statisticsFunctions/variance/cvariancea.c b/src/statisticsFunctions/variance/cvariancea.c
new file mode 100644
index 00000000..bff8c91f
--- /dev/null
+++ b/src/statisticsFunctions/variance/cvariancea.c
@@ -0,0 +1,50 @@
+/*
+ *  Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
+ *  Copyright (C) 2008-2008 - INRIA - Allan SIMON
+ *
+ *  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
+ *
+ */
+
+#include "variance.h"
+
+floatComplex	cvariancea(floatComplex *in, int size)
+{
+    int i = 0 ;
+    
+    /*here sumcis used to compensate the possible round off error to a less
+     important degree */
+    
+    floatComplex sum  = FloatComplex ( 0 , 0 ) ;
+    floatComplex temp = FloatComplex ( 0 , 0 ) ; 
+    floatComplex sumc = FloatComplex ( 0 , 0 ) ;
+    floatComplex variance = FloatComplex ( 0 , 0 );
+    floatComplex mean =  cmeana ( in , size ) ;
+     
+    for ( i = 0 ; i < size ; i++)
+    {
+
+       temp = cdiffs( in[i] , mean ) ;
+       sum  = cadds ( sum , cpows ( temp  , FloatComplex ( 2.0f, 0) ) );
+       sumc = cadds ( sumc , temp ); 
+        printf ( "%d r : %e  i : %e\n" , i , creals(in[i]) , cimags (in[i])); 
+    }
+    printf ( "\n\n" ) ;
+   /*we don't use sumc if equal to 0 otherwise we would have "nan" */
+   if ( fabs ( creals ( sumc)) > 1e-08 || fabs ( cimags ( sumc)) > 1e-08 )
+    {
+    variance = cpows ( sumc ,FloatComplex (2.0f , 0)) ;     
+    variance = cdevides ( variance  , FloatComplex ((float) size , 0 ) ) ;           
+    variance =  cdiffs ( sum , variance );      
+    variance = cdevides (variance , FloatComplex ((float) (size - 1),0 )); 
+    }
+   else 
+          variance = cdevides (sum , FloatComplex ((float) (size - 1),0 ));
+  
+    return variance ;
+}
+