From 78fcc4451906fd4fbc2830fc72fd511563d9bf98 Mon Sep 17 00:00:00 2001
From: hackbard <hackbard>
Date: Fri, 9 May 2003 15:15:15 +0000
Subject: [PATCH] fixed delta e bug

---
 Makefile |  4 ++--
 ising.c  | 22 +++++++++++++---------
 2 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/Makefile b/Makefile
index 5419453..95124d1 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 # ising Makefile
 
-INCLUDEDIR = /usr/include
-CFLAGS = -DDEBUG -DUSE_DFB_API -DFONT=\"./decker.ttf\" -O3 -Wall -I/usr/include/directfb
+INCLUDEDIR = /usr/local/include
+CFLAGS = -DDEBUG -DUSE_DFB_API -DFONT=\"./decker.ttf\" -O3 -Wall -I/usr/local/include/directfb
 LIBS = -L/usr/lib -ldirectfb
 
 OBJS = dfbapi.o
diff --git a/ising.c b/ising.c
index dd538b3..e43b4be 100644
--- a/ising.c
+++ b/ising.c
@@ -11,11 +11,12 @@
 #include <stdlib.h>
 #include <string.h>
 #include <math.h>
+#include <time.h>
 #include "dfbapi.h"
 
-#define X 100
-#define Y 100
-#define MAX_T 200
+#define X 200
+#define Y 200
+#define MAX_T 100
 
 int main(int argc, char **argv)
 {
@@ -33,6 +34,9 @@ int main(int argc, char **argv)
  double beta;
  double delta_e;
 
+ /* random stuff*/
+ srand(time(0));
+
  /* display stuff */
  d2_lattice d2_l;
 
@@ -53,9 +57,9 @@ int main(int argc, char **argv)
  
  for(T=1;T<MAX_T;T++)
  {
-  beta=1.0/T; /* k_B = 1 */
-  /* do 100 itterations, we will need more */
-  for(i=0;i<100;i++)
+  beta=20.0/T; /* k_B = 1 */
+  /* do 10 itterations, we will need more */
+  for(i=0;i<10;i++)
   {
 
  for(x_c=0;x_c<max_x;x_c++)
@@ -69,21 +73,21 @@ int main(int argc, char **argv)
    if((*(atom+((2*x_c+1)%max_x)+y_c*max_x))&1) ++count_p;
    if((*(atom+((2*x_c-1)%max_x)+y_c*max_x))&1) ++count_p;
    if(((*(atom+x_c+y_c*max_x))&1)==0) count_p=4-count_p;
-   delta_e=(4-2*count_p)*S;
+   delta_e=(2*count_p-4)*S;
    if(delta_e<0) *(atom+x_c+y_c*max_x)=(*(atom+x_c+y_c*max_x)+1)&1;
    else
    {
     if(1.0*rand()/RAND_MAX<exp(-1.0*delta_e*beta))
      *(atom+x_c+y_c*max_x)=(*(atom+x_c+y_c*max_x)+1)&1;
-    else M+=1;
    }
+   if((*(atom+x_c+((2*y_c+1)%max_y)*max_x))&1) ++M;
   }
  }
   sprintf(t_text,"T = %d",T);
   arg_v[1]=t_text;
   sprintf(b_text,"b = %f",beta);
   arg_v[2]=b_text;
-  sprintf(m_text,"M = %f",1.0-2*M/(max_x*max_y));
+  sprintf(m_text,"M = %f",1.0-2.0*M/(max_x*max_y));
   arg_v[3]=m_text;
   d2_lattice_draw(&d2_l,0,0,3,arg_v);
   }
-- 
2.20.1