From d91e829bff8e1cf9bfa003856ed89803234b83e5 Mon Sep 17 00:00:00 2001
From: Niko Abeler <niko@rerere.org>
Date: Thu, 17 Nov 2022 20:28:32 +0100
Subject: [PATCH] small refinements

---
 src/main.rs  | 51 ++++++++++++++++++++++++---------------------------
 src/utils.rs | 14 +++++++-------
 2 files changed, 31 insertions(+), 34 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index ef446cc..cd7e616 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,8 +1,8 @@
-use std::thread;
-use std::sync::{Arc, RwLock};
 use rand::Rng;
 use std::fs::File;
 use std::io::prelude::*;
+use std::sync::{Arc, RwLock};
+use std::thread;
 
 mod utils;
 
@@ -34,7 +34,7 @@ fn connection_matrix(size: usize) -> EdgeMatrix {
     for _ in 0..size {
         let mut row = Vec::with_capacity(size);
         for _ in 0..size {
-            row.push(Edge { weight: 0.0});
+            row.push(Edge { weight: 0.0 });
         }
         matrix.push(row);
     }
@@ -69,19 +69,20 @@ fn read_graph(file_name: &str) -> (usize, EdgeMatrix) {
 }
 
 fn main() -> std::io::Result<()> {
-
     const C_REP: f32 = 0.1;
     const C_SPRING: f32 = 0.1;
     const ITER: usize = 200;
     const THREADS: usize = 8;
-    
+
     // let edges = connection_matrix(size);
     let (size, edges): (usize, EdgeMatrix) = read_graph("../graph.bin");
     println!("Size: {}", size);
     let nodes = nodes_list(size);
     let nodes_next = nodes_list(size);
 
-    let chunks = utils::chunk_borders(size, THREADS);
+    let opt_dist = 10.0 / (size as f32).sqrt();
+
+    let chunks = utils::gen_chunks(size, THREADS);
     for epoch in 0..ITER {
         let mut handles = vec![];
         for i in 0..THREADS {
@@ -93,10 +94,10 @@ fn main() -> std::io::Result<()> {
                 for n in chunk {
                     let node = nodes[n].read().unwrap();
                     let edges = edges.read().unwrap();
-    
+
                     let mut node_x = node.x;
                     let mut node_y = node.y;
-    
+
                     for o in 0..size {
                         if o == n {
                             continue;
@@ -108,31 +109,29 @@ fn main() -> std::io::Result<()> {
                             o_x = other.x;
                             o_y = other.y;
                         }
-    
+
                         let d_x = o_x - node_x;
                         let d_y = o_y - node_y;
-                        let dist = (d_x * d_x + d_y * d_y).sqrt().max(0.01);
+                        let dist = (d_x * d_x + d_y * d_y).sqrt().max(0.0001);
                         let unit_x = d_x / dist;
                         let unit_y = d_y / dist;
-                        
-                        let f_rep = C_REP/(dist).powi(2);
-                        let f_rep_x = f_rep * unit_x;
-                        let f_rep_y = f_rep * unit_y;
-    
-                        node_x += f_rep_x;
-                        node_y += f_rep_y;
-    
+
                         let edge = edges[n][o].weight;
-                        if edge > 0.0 {
-                            let f_spring = C_SPRING * (dist / edge).log(2.0);
+
+                        if edge == 0.0 {
+                            let f_rep = -C_REP / (dist).powi(2);
+                            let f_rep_x = f_rep * unit_x;
+                            let f_rep_y = f_rep * unit_y;
+    
+                            node_x += f_rep_x;
+                            node_y += f_rep_y;
+                        } else {
+                            let f_spring = C_SPRING * (dist / opt_dist).log(2.0);
                             let f_spring_x = f_spring * unit_x;
                             let f_spring_y = f_spring * unit_y;
-    
-    
                             node_x += f_spring_x;
                             node_y += f_spring_y;
                         }
-    
                     }
                     let mut result = nodes_next[n].write().unwrap();
                     result.x = node_x;
@@ -141,11 +140,11 @@ fn main() -> std::io::Result<()> {
             });
             handles.push(handle);
         }
-    
+
         for handle in handles {
             handle.join().unwrap();
         }
-    
+
         for i in 0..size {
             let mut node = nodes[i].write().unwrap();
             let node_next = nodes_next[i].read().unwrap();
@@ -153,7 +152,6 @@ fn main() -> std::io::Result<()> {
             node.y = node_next.y;
         }
 
-
         let mut file = File::create(format!("result/{:04}.txt", epoch))?;
         for i in 0..size {
             let node = nodes[i].read().unwrap();
@@ -163,5 +161,4 @@ fn main() -> std::io::Result<()> {
     }
 
     Ok(())
-
 }
diff --git a/src/utils.rs b/src/utils.rs
index 3712acd..2e2be32 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -1,6 +1,6 @@
 use std::ops::Range;
 
-pub fn chunk_borders(n: usize, chunks: usize) -> Vec<Range<usize>> {
+pub fn gen_chunks(n: usize, chunks: usize) -> Vec<Range<usize>> {
     let mut borders = vec![];
     let chunk_size = n / chunks;
     let mut start = 0;
@@ -20,20 +20,20 @@ mod test {
     use super::*;
 
     #[test]
-    fn test_chunk_borders() {
-        let borders = chunk_borders(10, 3);
+    fn test_gen_chunks() {
+        let borders = gen_chunks(10, 3);
         assert_eq!(borders, vec![(0..3), (3..6), (6..10)]);
     }
 
     #[test]
-    fn test_chunk_borders2() {
-        let borders = chunk_borders(10, 2);
+    fn test_gen_chunks2() {
+        let borders = gen_chunks(10, 2);
         assert_eq!(borders, vec![(0..5), (5..10)]);
     }
 
     #[test]
-    fn test_chunk_borders3() {
-        let borders = chunk_borders(10, 1);
+    fn test_gen_chunks3() {
+        let borders = gen_chunks(10, 1);
         assert_eq!(borders, vec![(0..10)]);
     }