Adjust parameterization for Haar-DWT correlation coefficient

NillionNetwork · Jun 3, 2024 · 3d6290c · 3d6290c
1 parent 7bd7bf8
commit 3d6290c
Showing 1 changed file with 3 additions and 12 deletions.
diff --git a/src/correlation_haar.rs b/src/correlation_haar.rs
@@ -23,7 +23,7 @@ fn main() {
 
     // ------- Client side ------- //
     let bit_width = 16;
-    let precision = 6;
+    let precision = 0;
 
     // Number of blocks per ciphertext
     let nb_blocks = bit_width / 2;
@@ -67,7 +67,7 @@ fn main() {
         .iter()
         .map(|&exp| ((exp as f64) - experience_mean).powi(2))
         .sum();
-    let experience_stddev = experience_variance.sqrt();
+    let experience_stddev = quantize(experience_variance.sqrt(), precision, bit_width as u8);
 
     // Offline: LUT genaration is offline cost.
     let lut_gen_start = Instant::now();
@@ -85,13 +85,7 @@ fn main() {
         precision,
         bit_width as u8,
         bit_width as u8,
-        &|x: f64| {
-            if x.abs() < 0.05 {
-                1.0 // avoid division with zero error.
-            } else {
-                scale as f64 / (x.sqrt() * experience_stddev)
-            }
-        },
+        &|x: f64| scale as f64 / (x.sqrt() * experience_stddev as f64),
     );
     let haar_lsb_lut_sqrt = wopbs_key.generate_lut_radix(&dummy, |x: u64| eval_lut(x, &haar_lsb));
     let haar_msb_lut_sqrt = wopbs_key.generate_lut_radix(&dummy, |x: u64| eval_lut(x, &haar_msb));
@@ -126,7 +120,6 @@ fn main() {
         &haar_lsb_lut_div,
         &haar_msb_lut_div,
     );
-
     // Cov = Sum_i^n (salary_i - mean(salary))(experience_i - mean(experience))
     let covariance = encrypted_salaries
         .iter()
@@ -151,7 +144,6 @@ fn main() {
             server_key.create_trivial_radix(0_u64, nb_blocks),
             |acc: RadixCiphertext, diff| server_key.add_parallelized(&acc, &diff),
         );
-
     // sigma_salary (or stddev) = sqrt(var_salary)
     // println!("salaries_variance_enc degree: {:?}", salaries_variance_enc.blocks()[0].degree);
     let salaries_stddev_enc = ct_lut_eval_haar_no_gen(
@@ -172,6 +164,5 @@ fn main() {
     // ------- Client side ------- //
     let correlation: u64 = client_key.decrypt(&correlation_enc);
     let correlation_final: f64 = unquantize(correlation, precision, bit_width as u8);
-
     println!("Correlation: {}", correlation_final / (scale as f64));
 }