diff --git a/Cargo.lock b/Cargo.lock
index cccde7e..bb1b67c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -75,7 +75,7 @@ dependencies = [
  "embassy-usb",
  "embedded-hal 1.0.0",
  "heapless 0.9.1",
- "libm",
+ "num",
  "panic-probe",
  "postcard-rpc",
  "static_cell",
@@ -776,6 +776,58 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8d5439c4ad607c3c23abf66de8c8bf57ba8adcd1f129e699851a6e43935d339d"
 
+[[package]]
+name = "num"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "35bd024e8b2ff75562e5f34e7f4905839deb4b22955ef5e73d2fea1b9813cb23"
+dependencies = [
+ "num-complex",
+ "num-integer",
+ "num-iter",
+ "num-rational",
+ "num-traits",
+]
+
+[[package]]
+name = "num-complex"
+version = "0.4.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "73f88a1307638156682bada9d7604135552957b7818057dcef22705b4d509495"
+dependencies = [
+ "num-traits",
+]
+
+[[package]]
+name = "num-integer"
+version = "0.1.46"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7969661fd2958a5cb096e56c8e1ad0444ac2bbcd0061bd28660485a44879858f"
+dependencies = [
+ "num-traits",
+]
+
+[[package]]
+name = "num-iter"
+version = "0.1.45"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1429034a0490724d0075ebb2bc9e875d6503c3cf69e235a8941aa757d83ef5bf"
+dependencies = [
+ "autocfg",
+ "num-integer",
+ "num-traits",
+]
+
+[[package]]
+name = "num-rational"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f83d14da390562dca69fc84082e73e548e1ad308d24accdedd2720017cb37824"
+dependencies = [
+ "num-integer",
+ "num-traits",
+]
+
 [[package]]
 name = "num-traits"
 version = "0.2.19"
@@ -783,6 +835,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "071dfc062690e90b734c0b2273ce72ad0ffa95f0c74596bc250dcfd960262841"
 dependencies = [
  "autocfg",
+ "libm",
 ]
 
 [[package]]
diff --git a/Cargo.toml b/Cargo.toml
index a40927a..aa1d418 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -22,7 +22,9 @@ bitflags = "2.9.4"
 postcard-rpc = {version = "0.11.15", features = ["embassy-usb-0_4-server", "defmt"]}
 bioz-icd-rs = {path = "../bioz-icd-rs"}
 
-libm = { version = "0.2.15" }
+# libm = { version = "0.2.15" }
+
+num = {version = "0.4.3", default-features = false, features = ["libm"]}
 
 heapless = { version = "0.9.1" }
 
diff --git a/src/impedance.rs b/src/impedance.rs
index a5b9834..8e2c51d 100644
--- a/src/impedance.rs
+++ b/src/impedance.rs
@@ -10,6 +10,8 @@ use static_cell::StaticCell;
 
 use heapless::Vec;
 
+use num::complex::Complex;
+
 use crate::ad5940::*;
 use crate::ad5940_registers::*;
 
@@ -386,14 +388,6 @@ pub async fn impedance_setup_readout_task(mut pin: ExtiInput<'static>, impedance
     }
 }
 
-extern crate libm;
-
-#[derive(Debug, Clone, Copy)]
-pub struct Complex {
-    real: i32,
-    imag: i32,
-}
-
 #[derive(Debug)]
 pub struct ImpedanceResult {
     pub magnitude: f32,
@@ -410,29 +404,20 @@ fn sign_extend_18bit(val: u32) -> i32 {
 
 /// Calculate magnitude and phase of Rz using Rcal reference
 pub fn calculate_impedance(data: [u32; 4]) -> ImpedanceResult {
-    let mut signed_data = [0i32; 4];
-    for (i, &val) in data.iter().enumerate() {
-        signed_data[i] = sign_extend_18bit(val);
-    }
+    let dft_rcal = Complex::new(
+        sign_extend_18bit(data[0]) as f32, 
+        sign_extend_18bit(data[1]) as f32
+    );
+    let dft_rz = Complex::new(
+        sign_extend_18bit(data[2]) as f32, 
+        sign_extend_18bit(data[3]) as f32
+    );
 
-    let dft_rcal = Complex {
-        real: signed_data[0],
-        imag: signed_data[1],
-    };
+    let rcal_mag = dft_rcal.norm();
+    let rz_mag = dft_rz.norm();
 
-    let dft_rz = Complex {
-        real: signed_data[2],
-        imag: signed_data[3],
-    };
-
-    let rcal_mag = libm::sqrtf((dft_rcal.real as f32) * (dft_rcal.real as f32)
-                             + (dft_rcal.imag as f32) * (dft_rcal.imag as f32));
-
-    let rz_mag = libm::sqrtf((dft_rz.real as f32) * (dft_rz.real as f32)
-                           + (dft_rz.imag as f32) * (dft_rz.imag as f32));
-
-    let rcal_phase = libm::atan2f(-(dft_rcal.imag as f32), dft_rcal.real as f32);
-    let rz_phase = libm::atan2f(-(dft_rz.imag as f32), dft_rz.real as f32);
+    let rcal_phase = dft_rcal.arg();
+    let rz_phase = dft_rz.arg();
 
     let magnitude = (rcal_mag / rz_mag) * RCAL_VAL;
     let phase = rcal_phase - rz_phase;