From 4d9fc9de8a8afc82b4e02c2433e7139be8fc45d1 Mon Sep 17 00:00:00 2001
From: Patrice Matz <ofjokg@gmail.com>
Date: Thu, 4 Jan 2018 22:53:27 +0100
Subject: [PATCH] - added 2.2 cramer

---
 Mex/a22.cpp | 120 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 120 insertions(+)
 create mode 100644 Mex/a22.cpp

diff --git a/Mex/a22.cpp b/Mex/a22.cpp
new file mode 100644
index 0000000..792685c
--- /dev/null
+++ b/Mex/a22.cpp
@@ -0,0 +1,120 @@
+#include "mex.h" 
+#include "matrix.h"
+#include "stdlib.h"
+
+
+double** CA;
+double** CA2;
+double* x;
+int variables;
+	
+	
+void copy_array()
+{
+	for (int i = 0; i < variables; ++i)
+		for (int n = 0; n < variables + 1; ++n)
+			CA2[i][n] = CA[i][n];
+}
+
+void swap_column(double** ca2, int col)
+{
+	double* temp = (double *)mxCalloc(variables, sizeof(double));
+	copy_array();
+	for(int i=0; i < variables ;i++)
+	{
+		temp[i] = CA[i][variables];
+	}
+	for(int i=0; i < variables ;i++)
+	{
+		CA2[i][col] = temp[i];
+	}
+	free(temp);
+}
+
+double determinant(double** ga, int m)   
+{
+
+	double sum = 0;
+	double** t = (double **)mxCalloc(variables, sizeof(double*));		
+	for (int i = 0; i < variables; ++i)
+		t[i] = (double *)mxCalloc(variables, sizeof(double));
+	
+
+	if (m == 2)
+	{												
+		sum = ga[0][0] * ga[1][1] - ga[0][1] * ga[1][0];
+		return sum;
+	}
+	for (int p = 0; p<m; p++)
+	{
+		int h = 0, k = 0;
+		for (int i = 1; i<m; i++)
+		{
+			for (int j = 0; j<m; j++)
+			{
+				if (j == p)
+					continue;
+				t[h][k] = ga[i][j];
+				k++;
+				if (k == m - 1)
+				{
+					h++;
+					k = 0;
+				}
+
+			}
+		}
+
+		sum = sum + ga[0][p] * pow(-1, p)*determinant(t, m - 1);
+	}
+	return sum;
+}
+
+void mexFunction(int nlhs, mxArray *plhs[], 			// Output variables 
+				 int nrhs, const mxArray *prhs[]) 		// Input variables 
+{
+	variables = *mxGetPr(prhs[0]);
+	
+	double* x = (double *)mxCalloc(variables, sizeof(double));
+
+	CA = (double **)mxCalloc(variables, sizeof(double*));			//create original array
+	CA2 = (double **)mxCalloc(variables, sizeof(double*));			//create working array
+	
+	for (int i = 0; i <= variables; i++){
+		CA[i] = (double *)mxCalloc(variables, sizeof(double));
+	}					
+	for (int i = 0; i <= variables; i++){									
+		CA2[i] = (double *)mxCalloc(variables, sizeof(double));
+	}
+	
+	for(int i = 0; i < variables*(variables+1); i++){				//copy input array into ca and ca2							
+		CA[i%variables][i/variables] = mxGetPr(prhs[1])[i];	
+		CA2[i%variables][i/variables] = mxGetPr(prhs[1])[i];
+	}
+	//Actual cramer
+	
+	double detA = determinant(CA,variables);
+	
+	copy_array();
+
+	for(int i = 0; i < variables; i++)
+	{
+		swap_column(CA2, i);
+		x[i] = determinant(CA2, variables);
+	}
+
+	// Output
+	for(int j=0; j < variables; j++){
+		plhs[j]=mxCreateDoubleScalar(x[j]/detA );
+		
+	} 
+	// free memory
+	for (int i = 0; i <= variables; i++ ){
+		free(CA2[i]);
+	}
+	
+	free(CA2);
+	free(x);
+  
+return;
+}
\ No newline at end of file