From 3e53256e53dfbd2c858866808f443fef5c55dfd3 Mon Sep 17 00:00:00 2001
From: Ishan Jain <contact@ishanjain.me>
Date: Wed, 31 May 2023 10:57:29 +0530
Subject: [PATCH] testing pdfs

---
 src/main.rs | 37 +++++++++++--------------------------
 1 file changed, 11 insertions(+), 26 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index 41689f3..76d6d58 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,35 +1,20 @@
 use rand::Rng;
 
+#[inline]
+fn pdf(x: f64) -> f64 {
+    3.0 * x * x / 8.0
+}
+
 fn main() {
-    let mut inside_circle = 0u64;
-    let mut inside_circle_stratified = 0u64;
     let mut rng = rand::thread_rng();
+    const N: u64 = 100000;
+    let mut sum = 0.0;
 
-    const SQRT_N: u64 = 10000;
+    for _ in 0..N {
+        let x: f64 = rng.gen_range(0.0f64..=8.0).powf(1.0 / 3.0);
 
-    for i in 0..SQRT_N {
-        for j in 0..SQRT_N {
-            let mut x: f64 = rng.gen_range(-1.0..=1.0);
-            let mut y: f64 = rng.gen_range(-1.0..=1.0);
-
-            if x * x + y * y < 1.0 {
-                inside_circle += 1;
-            }
-
-            x = (2.0f64 * (i as f64 + rng.gen::<f64>()) / SQRT_N as f64) - 1.0;
-            y = (2.0f64 * (j as f64 + rng.gen::<f64>()) / SQRT_N as f64) - 1.0;
-
-            if x * x + y * y < 1.0 {
-                inside_circle_stratified += 1;
-            }
-        }
+        sum += x * x / pdf(x);
     }
 
-    let n = SQRT_N as f64 * SQRT_N as f64;
-
-    println!(
-        "regular estimation = {} stratified estimate = {}",
-        4.0 * inside_circle as f64 / n,
-        4.0 * inside_circle_stratified as f64 / n
-    );
+    println!("answer = {}", sum / N as f64);
 }