From 3c845bf493856da2de260f56f60d11a6c746ccef Mon Sep 17 00:00:00 2001
From: tomsmeding <tom.smeding@gmail.com>
Date: Wed, 5 Apr 2017 15:58:57 +0200
Subject: Make exponent variable

---
 attract.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/attract.c b/attract.c
index 16f1703..47f4a42 100644
--- a/attract.c
+++ b/attract.c
@@ -15,7 +15,7 @@
 const int MAXITER=200;
 const double EPS=1e-1;
 
-static double complex att_func(double complex x){
+static double complex att_func(double complex x,double exponent){
 #if 0
 	static const int N=9;
 
@@ -27,8 +27,7 @@ static double complex att_func(double complex x){
 	r+=y;
 	return clog(r);
 #else
-	static const double N=8.5;
-	return clog((1-cpow(x,N+1))/(1-x));
+	return clog((1-cpow(x,exponent+1))/(1-x));
 #endif
 }
 
@@ -49,8 +48,9 @@ static struct colour make_colour(int index){
 }
 
 struct config{
-	const double unitsz;
-	const int width,height;
+	double unitsz;
+	int width,height;
+	double exponent;
 };
 
 struct thread_info{
@@ -86,7 +86,7 @@ static void* thread_entry(void *arg_vp){
 					(double)(iy-cfg.height/2)/cfg.unitsz);
 			double complex z=start;
 			for(int i=0;i<MAXITER;i++){
-				z=att_func(z);
+				z=att_func(z,cfg.exponent);
 			}
 			if(do_basins){
 				int bi;
@@ -121,8 +121,9 @@ static void* thread_entry(void *arg_vp){
 
 int main(void){
 	struct config cfg={
-		200,
-		500, 500
+		.unitsz=200,
+		.width=500, .height=500,
+		.exponent=8.5
 	};
 
 	unsigned char img[cfg.width*cfg.height*3];
@@ -145,7 +146,7 @@ int main(void){
 		ths[i].yend=(i+1)*cfg.height/nthreads;
 		ths[i].img=img;
 		ths[i].do_basins=nthreads==1;
-		memcpy(&ths[i].cfg,&cfg,sizeof(struct config));
+		ths[i].cfg=cfg;
 		int ret=pthread_create(&ths[i].th,&attr,thread_entry,&ths[i]);
 		if(ret!=0){
 			perror("pthread_create");
-- 
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