diff --git a/src/si/ratio.rs b/src/si/ratio.rs
index 47abeba9..bd789871 100644
--- a/src/si/ratio.rs
+++ b/src/si/ratio.rs
@@ -32,49 +32,117 @@ quantity! {
     }
 }
 
-/// Implementation of various stdlib inverse trigonometric functions
+/// Implementation of various stdlib functions.
 #[cfg(feature = "std")]
 impl<U, V> Ratio<U, V>
 where
     U: crate::si::Units<V> + ?Sized,
     V: crate::num::Float + crate::Conversion<V>,
     radian: crate::Conversion<V, T = V::T>,
+    ratio: crate::Conversion<V, T = V::T>,
 {
     /// Computes the value of the inverse cosine of the ratio.
+    #[must_use = "method returns a new number and does not mutate the original value"]
     #[inline(always)]
     pub fn acos(self) -> Angle<U, V> {
         Angle::new::<radian>(self.value.acos())
     }
 
     /// Computes the value of the inverse hyperbolic cosine of the ratio.
+    #[must_use = "method returns a new number and does not mutate the original value"]
     #[inline(always)]
     pub fn acosh(self) -> Angle<U, V> {
         Angle::new::<radian>(self.value.acosh())
     }
 
     /// Computes the value of the inverse sine of the ratio.
+    #[must_use = "method returns a new number and does not mutate the original value"]
     #[inline(always)]
     pub fn asin(self) -> Angle<U, V> {
         Angle::new::<radian>(self.value.asin())
     }
 
     /// Computes the value of the inverse hyperbolic sine of the ratio.
+    #[must_use = "method returns a new number and does not mutate the original value"]
     #[inline(always)]
     pub fn asinh(self) -> Angle<U, V> {
         Angle::new::<radian>(self.value.asinh())
     }
 
     /// Computes the value of the inverse tangent of the ratio.
+    #[must_use = "method returns a new number and does not mutate the original value"]
     #[inline(always)]
     pub fn atan(self) -> Angle<U, V> {
         Angle::new::<radian>(self.value.atan())
     }
 
     /// Computes the value of the inverse hyperbolic tangent of the ratio.
+    #[must_use = "method returns a new number and does not mutate the original value"]
     #[inline(always)]
     pub fn atanh(self) -> Angle<U, V> {
         Angle::new::<radian>(self.value.atanh())
     }
+
+    /// Returns `e^(self)`, (the exponential function).
+    #[must_use = "method returns a new number and does not mutate the original value"]
+    #[inline(always)]
+    pub fn exp(self) -> Ratio<U, V> {
+        Ratio::new::<ratio>(self.value.exp())
+    }
+
+    /// Returns 2^(self).
+    #[must_use = "method returns a new number and does not mutate the original value"]
+    #[inline(always)]
+    pub fn exp2(self) -> Ratio<U, V> {
+        Ratio::new::<ratio>(self.value.exp2())
+    }
+
+    /// Returns the natural logarithm of the number.
+    #[must_use = "method returns a new number and does not mutate the original value"]
+    #[inline(always)]
+    pub fn ln(self) -> Ratio<U, V> {
+        Ratio::new::<ratio>(self.value.ln())
+    }
+
+    /// Returns the logarithm of the number with respect to an arbitrary base.
+    ///
+    /// The result might not be correctly rounded owing to implementation
+    /// details; self.log2() can produce more accurate results for base 2, and
+    /// self.log10() can produce more accurate results for base 10.
+    #[must_use = "method returns a new number and does not mutate the original value"]
+    #[inline(always)]
+    pub fn log(self, base: V) -> Ratio<U, V> {
+        Ratio::new::<ratio>(self.value.log(base))
+    }
+
+    /// Returns the base 2 logarithm of the number.
+    #[must_use = "method returns a new number and does not mutate the original value"]
+    #[inline(always)]
+    pub fn log2(self) -> Ratio<U, V> {
+        Ratio::new::<ratio>(self.value.log2())
+    }
+
+    /// Returns the base 10 logarithm of the number.
+    #[must_use = "method returns a new number and does not mutate the original value"]
+    #[inline(always)]
+    pub fn log10(self) -> Ratio<U, V> {
+        Ratio::new::<ratio>(self.value.log10())
+    }
+
+    /// Returns e^(self) - 1 in a way that is accurate even if the number is close to zero.
+    #[must_use = "method returns a new number and does not mutate the original value"]
+    #[inline(always)]
+    pub fn exp_m1(self) -> Ratio<U, V> {
+        Ratio::new::<ratio>(self.value.exp_m1())
+    }
+
+    /// Returns ln(1+n) (natural logarithm) more accurately than if the
+    /// operations were performed separately.
+    #[must_use = "method returns a new number and does not mutate the original value"]
+    #[inline(always)]
+    pub fn ln_1p(self) -> Ratio<U, V> {
+        Ratio::new::<ratio>(self.value.ln_1p())
+    }
 }
 
 mod convert {
@@ -153,11 +221,12 @@ mod tests {
     }
 
     #[cfg(feature = "std")]
-    mod inv_trig {
+    mod float {
         storage_types! {
             types: Float;
 
             use crate::si::angle as a;
+            use crate::si::ratio as r;
             use crate::si::quantities::*;
             use crate::tests::Test;
 
@@ -185,6 +254,38 @@ mod tests {
                 fn atanh(x: V) -> bool {
                     Test::eq(&x.atanh(), &Ratio::from(x).atanh().get::<a::radian>())
                 }
+
+                fn exp(x: V) -> bool {
+                    Test::eq(&x.exp(), &Ratio::from(x).exp().get::<r::ratio>())
+                }
+
+                fn exp2(x: V) -> bool {
+                    Test::eq(&x.exp2(), &Ratio::from(x).exp2().get::<r::ratio>())
+                }
+
+                fn ln(x: V) -> bool {
+                    Test::eq(&x.ln(), &Ratio::from(x).ln().get::<r::ratio>())
+                }
+
+                fn log(x: V, y: V) -> bool {
+                    Test::eq(&x.log(y), &Ratio::from(x).log(y).get::<r::ratio>())
+                }
+
+                fn log2(x: V) -> bool {
+                    Test::eq(&x.log2(), &Ratio::from(x).log2().get::<r::ratio>())
+                }
+
+                fn log10(x: V) -> bool {
+                    Test::eq(&x.log10(), &Ratio::from(x).log10().get::<r::ratio>())
+                }
+
+                fn exp_m1(x: V) -> bool {
+                    Test::eq(&x.exp_m1(), &Ratio::from(x).exp_m1().get::<r::ratio>())
+                }
+
+                fn ln_1p(x: V) -> bool {
+                    Test::eq(&x.ln_1p(), &Ratio::from(x).ln_1p().get::<r::ratio>())
+                }
             }
         }
     }