diff --git a/src/gamma.rs b/src/gamma.rs
index ea06539e..64dc1612 100644
--- a/src/gamma.rs
+++ b/src/gamma.rs
@@ -7,6 +7,9 @@ pub trait Gamma
 where
     Self: Sized,
 {
+    /// Compute the gamma function.
+    fn gamma(self) -> Self;
+
     /// Compute the real-valued digamma function.
     ///
     /// The formula is as follows:
@@ -35,8 +38,12 @@ where
     ///    inference. University of London, 2003, pp. 265–266.
     fn digamma(self) -> Self;
 
-    /// Compute the gamma function.
-    fn gamma(self) -> Self;
+    /// Compute the trigamma function.
+    ///
+    /// The code is based on a [Julia implementation][1].
+    ///
+    /// [1]: https://github.com/JuliaMath/SpecialFunctions.jl
+    fn trigamma(&self) -> Self;
 
     /// Compute the regularized lower incomplete gamma function.
     ///
@@ -61,13 +68,6 @@ where
 
     /// Compute the natural logarithm of the gamma function.
     fn ln_gamma(self) -> (Self, i32);
-
-    /// Compute the trigamma function.
-    ///
-    /// The code is based on a [Julia implementation][1].
-    ///
-    /// [1]: https://github.com/JuliaMath/SpecialFunctions.jl
-    fn trigamma(&self) -> Self;
 }
 
 macro_rules! evaluate_polynomial(
@@ -78,6 +78,11 @@ macro_rules! evaluate_polynomial(
 
 #[rustfmt::skip]
 macro_rules! implement { ($kind:ty) => { impl Gamma for $kind {
+    #[inline]
+    fn gamma(self) -> Self {
+        self.tgamma()
+    }
+
     fn digamma(self) -> Self {
         let p = self;
         if p <= 8.0 {
@@ -102,9 +107,40 @@ macro_rules! implement { ($kind:ty) => { impl Gamma for $kind {
             )
     }
 
-    #[inline]
-    fn gamma(self) -> Self {
-        self.tgamma()
+    fn trigamma(&self) -> Self {
+        let mut x: $kind = *self;
+        if x <= 0.0 {
+            return (<$kind>::PI * (<$kind>::PI * x).sin().recip()).powi(2)
+                - (1.0 - x).trigamma();
+        }
+
+        let mut psi: $kind = 0.0;
+        if x < 8.0 {
+            let n = (8.0 - x.floor()) as usize;
+            psi += x.recip().powi(2);
+            for v in 1..n {
+                psi += (x + (v as $kind)).recip().powi(2);
+            }
+            x += n as $kind;
+        }
+        let t = x.recip();
+        let w = t * t;
+        psi += t + 0.5 * w;
+        psi + t
+            * w
+            * evaluate_polynomial!(
+                w,
+                [
+                    0.16666666666666666,
+                    -0.03333333333333333,
+                    0.023809523809523808,
+                    -0.03333333333333333,
+                    0.07575757575757576,
+                    -0.2531135531135531,
+                    1.1666666666666667,
+                    -7.092156862745098,
+                ]
+            )
     }
 
     fn inc_gamma(self, p: Self) -> Self {
@@ -205,42 +241,6 @@ macro_rules! implement { ($kind:ty) => { impl Gamma for $kind {
     fn ln_gamma(self) -> (Self, i32) {
         self.lgamma()
     }
-
-    fn trigamma(&self) -> Self {
-        let mut x: $kind = *self;
-        if x <= 0.0 {
-            return (<$kind>::PI * (<$kind>::PI * x).sin().recip()).powi(2)
-                - (1.0 - x).trigamma();
-        }
-
-        let mut psi: $kind = 0.0;
-        if x < 8.0 {
-            let n = (8.0 - x.floor()) as usize;
-            psi += x.recip().powi(2);
-            for v in 1..n {
-                psi += (x + (v as $kind)).recip().powi(2);
-            }
-            x += n as $kind;
-        }
-        let t = x.recip();
-        let w = t * t;
-        psi += t + 0.5 * w;
-        psi + t
-            * w
-            * evaluate_polynomial!(
-                w,
-                [
-                    0.16666666666666666,
-                    -0.03333333333333333,
-                    0.023809523809523808,
-                    -0.03333333333333333,
-                    0.07575757575757576,
-                    -0.2531135531135531,
-                    1.1666666666666667,
-                    -7.092156862745098,
-                ]
-            )
-    }
 }}}
 
 implement!(f32);
@@ -263,6 +263,51 @@ mod tests {
         assert_eq!(-FRAC_PI_2 - 3.0 * LN_2 - EULER_MASCHERONI, 0.25.digamma());
     }
 
+    #[test]
+    fn trigamma() {
+        #[cfg(feature = "no_std")]
+        use core::f64::consts::PI;
+        #[cfg(not(feature = "no_std"))]
+        use std::f64::consts::PI;
+        let x = vec![
+            0.1,
+            0.5,
+            1.0,
+            2.0,
+            3.0,
+            4.0,
+            5.0,
+            6.0,
+            7.0,
+            8.0,
+            9.0,
+            10.0,
+            -PI,
+            -2.0 * PI,
+            -3.0 * PI,
+        ];
+        let y = vec![
+            101.43329915079276,
+            4.93480220054468,
+            1.6449340668482262,
+            0.6449340668482261,
+            0.39493406684822613,
+            0.28382295573711497,
+            0.221322955737115,
+            0.18132295573711496,
+            0.1535451779593372,
+            0.13313701469403108,
+            0.11751201469403139,
+            0.10516633568168575,
+            53.030438740085536,
+            16.206759250472963,
+            10.341296000533267,
+        ];
+
+        let z = x.iter().map(|&x| x.trigamma()).collect::<Vec<_>>();
+        assert::close(&z, &y, 1e-12);
+    }
+
     #[test]
     fn inc_gamma_small_p() {
         let p = 4.2;
@@ -330,49 +375,4 @@ mod tests {
         let z = x.iter().map(|&x| x.inc_gamma(p)).collect::<Vec<_>>();
         assert::close(&z, &y, 1e-12);
     }
-
-    #[test]
-    fn trigamma() {
-        #[cfg(feature = "no_std")]
-        use core::f64::consts::PI;
-        #[cfg(not(feature = "no_std"))]
-        use std::f64::consts::PI;
-        let x = vec![
-            0.1,
-            0.5,
-            1.0,
-            2.0,
-            3.0,
-            4.0,
-            5.0,
-            6.0,
-            7.0,
-            8.0,
-            9.0,
-            10.0,
-            -PI,
-            -2.0 * PI,
-            -3.0 * PI,
-        ];
-        let y = vec![
-            101.43329915079276,
-            4.93480220054468,
-            1.6449340668482262,
-            0.6449340668482261,
-            0.39493406684822613,
-            0.28382295573711497,
-            0.221322955737115,
-            0.18132295573711496,
-            0.1535451779593372,
-            0.13313701469403108,
-            0.11751201469403139,
-            0.10516633568168575,
-            53.030438740085536,
-            16.206759250472963,
-            10.341296000533267,
-        ];
-
-        let z = x.iter().map(|&x| x.trigamma()).collect::<Vec<_>>();
-        assert::close(&z, &y, 1e-12);
-    }
 }