diff --git a/kalk/scripts/generate_funcs_test_cases.py b/kalk/scripts/generate_funcs_test_cases.py
new file mode 100755
index 0000000..c05806f
--- /dev/null
+++ b/kalk/scripts/generate_funcs_test_cases.py
@@ -0,0 +1,65 @@
+#!/bin/python
+
+from random import randint
+import mpmath
+
+
+funcs = [
+    (mpmath.arg, "arg"),
+    (mpmath.ceil, "ceil"),
+    (mpmath.exp, "exp"),
+    (mpmath.floor, "floor"),
+    (mpmath.log10, "log"),
+    (mpmath.ln, "ln"),
+    (mpmath.sqrt, "sqrt"),
+    (mpmath.acos, "acos"),
+    (mpmath.acosh, "acosh"),
+    (mpmath.acsc, "acsc"),
+    (mpmath.acsch, "acsch"),
+    (mpmath.acot, "acot"),
+    (mpmath.acoth, "acoth"),
+    (mpmath.asec, "asec"),
+    (mpmath.asech, "asech"),
+    (mpmath.asin, "asin"),
+    (mpmath.asinh, "asinh"),
+    (mpmath.atan, "atan"),
+    (mpmath.atanh, "atanh"),
+    (mpmath.cos, "cos"),
+    (mpmath.cosh, "cosh"),
+    (mpmath.csc, "csc"),
+    (mpmath.csch, "csch"),
+    (mpmath.cot, "cot"),
+    (mpmath.coth, "coth"),
+    (mpmath.sec, "sec"),
+    (mpmath.sech, "sech"),
+    (mpmath.sin, "sin"),
+    (mpmath.sinh, "sinh"),
+    (mpmath.tan, "tan"),
+    (mpmath.tanh, "tanh"),
+]
+
+for func in funcs:
+    args = [
+        (randint(-10, 10) / 10, 0),
+        (0, randint(-10, 10) / 10),
+        (randint(-10, 10) / 10, randint(-10, 10) / 10),
+        (randint(-10, 10) / 10, randint(-10, 10) / 10),
+        (randint(15, 30) / 10, 0),
+        (randint(-30, -15) / 10, 0),
+        (0, 0)
+    ]
+
+    for arg in args:
+        result = 0
+        defined = True
+        try:
+            result = func[0](complex(arg[0], arg[1]))
+        except:
+            defined = False
+
+        print("({0}, ({1}f64, {2}f64), ({3}, {4})),".format(
+            func[1],
+            arg[0],
+            arg[1],
+            str(round(result.real, 7)) + "f64" if defined else "f64::NAN",
+            str(round(result.imag, 7)) + "f64" if defined else "f64::NAN"))
diff --git a/kalk/src/calculus.rs b/kalk/src/calculus.rs
index c8d05cc..57a3742 100644
--- a/kalk/src/calculus.rs
+++ b/kalk/src/calculus.rs
@@ -144,10 +144,6 @@ mod tests {
         )
     }
 
-    fn cmp(x: f64, y: f64) -> bool {
-        (x - y).abs() < 0.0001
-    }
-
     #[test]
     fn test_derive_func() {
         let mut symbol_table = SymbolTable::new();
diff --git a/kalk/src/interpreter.rs b/kalk/src/interpreter.rs
index a8f597e..f680d9a 100644
--- a/kalk/src/interpreter.rs
+++ b/kalk/src/interpreter.rs
@@ -272,25 +272,6 @@ pub(crate) fn eval_fn_call_expr(
     let prelude_func = match expressions.len() {
         1 => {
             let x = eval_expr(context, &expressions[0], "")?;
-
-            // Turn eg. sqrt(-1) into i
-            if x.value < 0f64 && (identifier.full_name == "sqrt" || identifier.full_name == "√") {
-                let abs_value = x.mul(context, KalkNum::from(-1f64));
-                let (sqrt, unit) = prelude::call_unary_func(
-                    context,
-                    &identifier.full_name,
-                    abs_value,
-                    &context.angle_unit.clone(),
-                )
-                .unwrap();
-
-                return Ok(KalkNum::new_with_imaginary(
-                    KalkNum::default().value,
-                    &unit,
-                    sqrt.value,
-                ));
-            }
-
             if identifier.prime_count > 0 {
                 return calculus::derive_func(context, &identifier, x);
             } else {
diff --git a/kalk/src/kalk_num/regular.rs b/kalk/src/kalk_num/regular.rs
index 3b36edf..0dd5332 100644
--- a/kalk/src/kalk_num/regular.rs
+++ b/kalk/src/kalk_num/regular.rs
@@ -23,7 +23,11 @@ impl KalkNum {
         Self {
             value,
             unit: unit.to_string(),
-            imaginary_value,
+            imaginary_value: if imaginary_value == -0f64 {
+                0f64
+            } else {
+                imaginary_value
+            },
         }
     }
 
diff --git a/kalk/src/kalk_num/with_rug.rs b/kalk/src/kalk_num/with_rug.rs
index b7686ee..c34b02c 100644
--- a/kalk/src/kalk_num/with_rug.rs
+++ b/kalk/src/kalk_num/with_rug.rs
@@ -26,7 +26,11 @@ impl KalkNum {
         Self {
             value,
             unit: unit.to_string(),
-            imaginary_value,
+            imaginary_value: if imaginary_value == -0f64 {
+                imaginary_value.abs()
+            } else {
+                imaginary_value
+            },
         }
     }
 
@@ -48,7 +52,7 @@ impl KalkNum {
     }
 
     pub fn to_i32(&self) -> i32 {
-        self.value.to_i32_saturating().unwrap()
+        self.value.to_i32_saturating().unwrap_or(0i32)
     }
 
     pub fn get_unit(&self) -> &str {
diff --git a/kalk/src/prelude/mod.rs b/kalk/src/prelude/mod.rs
index 2937dc0..493cf3d 100644
--- a/kalk/src/prelude/mod.rs
+++ b/kalk/src/prelude/mod.rs
@@ -234,7 +234,7 @@ pub mod funcs {
     }
 
     pub fn acos(x: KalkNum) -> KalkNum {
-        if x.has_imaginary() {
+        if x.has_imaginary() || x.value > 1f64 || x.value < -1f64 {
             // -i * ln(i * sqrt(1 - z²) + z)
             let root =
                 sqrt(KalkNum::from(1f64).sub_without_unit(x.clone().mul_without_unit(x.clone())));
@@ -249,7 +249,7 @@ pub mod funcs {
     }
 
     pub fn acosh(x: KalkNum) -> KalkNum {
-        if x.has_imaginary() {
+        if x.has_imaginary() || x.value < 1f64 {
             let sqrt1 = sqrt(KalkNum::new_with_imaginary(
                 x.value.clone() + 1f64,
                 &x.unit,
@@ -277,7 +277,7 @@ pub mod funcs {
     }
 
     pub fn acoth(x: KalkNum) -> KalkNum {
-        if x.has_imaginary() {
+        if x.has_imaginary() || x.value <= 1f64 || x.value >= -1f64 {
             // 1 / z
             let inv_x = KalkNum::from(1f64).div_without_unit(x);
             let ln1 = ln(KalkNum::new_with_imaginary(
@@ -299,7 +299,7 @@ pub mod funcs {
     }
 
     pub fn acsc(x: KalkNum) -> KalkNum {
-        if x.has_imaginary() {
+        if x.has_imaginary() || x.value < 1f64 || x.value > -1f64 {
             // asin(1/z)
             asin(KalkNum::from(1f64).div_without_unit(x))
         } else {
@@ -308,7 +308,7 @@ pub mod funcs {
     }
 
     pub fn acsch(x: KalkNum) -> KalkNum {
-        if x.has_imaginary() {
+        if x.has_imaginary() || x.value == 0f64 {
             let inv_x2 =
                 KalkNum::from(1f64).div_without_unit(x.clone().mul_without_unit(x.clone()));
             let sqrt = sqrt(KalkNum::new_with_imaginary(
@@ -325,7 +325,7 @@ pub mod funcs {
     }
 
     pub fn asec(x: KalkNum) -> KalkNum {
-        if x.has_imaginary() {
+        if x.has_imaginary() || x.value < 1f64 || x.value > -1f64 {
             // acos(1/z)
             acos(KalkNum::from(1f64).div_without_unit(x))
         } else {
@@ -334,7 +334,7 @@ pub mod funcs {
     }
 
     pub fn asech(x: KalkNum) -> KalkNum {
-        if x.has_imaginary() {
+        if x.has_imaginary() || x.value <= 0f64 || x.value > 1f64 {
             // 1/z
             let inv_x = KalkNum::from(1f64).div_without_unit(x.clone());
             // sqrt(1/z - 1)
@@ -358,7 +358,7 @@ pub mod funcs {
     }
 
     pub fn asin(x: KalkNum) -> KalkNum {
-        if x.has_imaginary() {
+        if x.has_imaginary() || x.value > 1f64 || x.value < -1f64 {
             // i * ln(sqrt(1 - z²) - iz)
             let root =
                 sqrt(KalkNum::from(1f64).sub_without_unit(x.clone().mul_without_unit(x.clone())));
@@ -388,26 +388,28 @@ pub mod funcs {
     pub fn atan(x: KalkNum) -> KalkNum {
         if x.has_imaginary() {
             let iz = multiply_with_i(x);
-            // 1 + iz
-            let numerator = KalkNum::new_with_imaginary(
-                1f64 + iz.value.clone(),
-                &iz.unit,
-                iz.imaginary_value.clone(),
-            );
-            // 1 - iz
-            let denominator =
-                KalkNum::new_with_imaginary(1f64 - iz.value, &iz.unit, -iz.imaginary_value);
-            let ln = ln(numerator.div_without_unit(denominator));
 
-            // -0.5iz = -0.5i(a + bi) = b/2 - ai/2
-            multiply_with_i(ln).div_without_unit(KalkNum::from(-2f64))
+            // 1 - iz
+            let neg = KalkNum::new_with_imaginary(
+                1f64 - iz.value.clone(),
+                &iz.unit,
+                -iz.imaginary_value.clone(),
+            );
+
+            // 1 + iz
+            let pos = KalkNum::new_with_imaginary(1f64 + iz.value, &iz.unit, iz.imaginary_value);
+
+            // ln(1 - iz) - ln(1 + iz)
+            let ln = ln(neg).sub_without_unit(ln(pos));
+
+            multiply_with_i(ln).div_without_unit(KalkNum::from(2f64))
         } else {
             KalkNum::new(x.value.atan(), &x.unit)
         }
     }
 
     pub fn atanh(x: KalkNum) -> KalkNum {
-        if x.has_imaginary() {
+        if x.has_imaginary() || x.value >= 1f64 || x.value <= -1f64 {
             // 1/2 * log(z + 1) - 1/2 * log(-z + 1)
             let log1 = ln(KalkNum::new_with_imaginary(
                 1f64 + x.value.clone(),
@@ -499,7 +501,7 @@ pub mod funcs {
     }
 
     pub fn log(x: KalkNum) -> KalkNum {
-        if x.has_imaginary() {
+        if x.has_imaginary() || x.value < 0f64 {
             // ln(z) / ln(10)
             ln(x).div_without_unit(KalkNum::from(10f64.ln()))
         } else {
@@ -508,7 +510,7 @@ pub mod funcs {
     }
 
     pub fn logx(x: KalkNum, y: KalkNum) -> KalkNum {
-        if x.has_imaginary() || y.has_imaginary() {
+        if x.has_imaginary() || y.has_imaginary() || x.value < 0f64 || y.value < 0f64 {
             // ln(z) / ln(n)
             ln(x).div_without_unit(ln(y))
         } else {
@@ -517,7 +519,7 @@ pub mod funcs {
     }
 
     pub fn ln(x: KalkNum) -> KalkNum {
-        if x.has_imaginary() {
+        if x.has_imaginary() || x.value < 0f64 {
             let r = abs(x.clone());
             // ln|z| + i * arg z
             ln(r).add_without_unit(multiply_with_i(arg(x)))
@@ -571,6 +573,8 @@ pub mod funcs {
                 &abs.unit,
                 (b.clone() / b.abs()) * ((r - a) / 2f64).sqrt(),
             )
+        } else if x.value < 0f64 {
+            KalkNum::from_imaginary(x.value.abs().sqrt())
         } else {
             KalkNum::new(x.value.sqrt(), &x.unit)
         }
@@ -613,3 +617,304 @@ pub mod funcs {
         KalkNum::new_with_imaginary(-z.imaginary_value, &z.unit, z.value)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::funcs::*;
+    use crate::prelude::KalkNum;
+    use crate::test_helpers::cmp;
+
+    #[test]
+    fn test_funcs() {
+        let in_out = vec![
+            (abs as fn(KalkNum) -> KalkNum, (3f64, 4f64), (5f64, 0f64)),
+            (abs, (-3f64, 4f64), (5f64, 0f64)),
+            (abs, (3f64, -4f64), (5f64, 0f64)),
+            (abs, (-3f64, 0f64), (3f64, 0f64)),
+        ];
+
+        for (i, (func, input, expected_output)) in in_out.iter().enumerate() {
+            let actual_output = func(KalkNum::new_with_imaginary(
+                KalkNum::from(input.0).value,
+                "",
+                KalkNum::from(input.1).value,
+            ));
+
+            println!(
+                "{} | expected: {}, {}",
+                i, expected_output.0, expected_output.1
+            );
+            println!(
+                "{} | got: {}, {}",
+                i,
+                actual_output.to_f64(),
+                actual_output.imaginary_to_f64()
+            );
+            assert!(cmp(expected_output.0, actual_output.to_f64()));
+            assert!(cmp(expected_output.1, actual_output.imaginary_to_f64()));
+        }
+    }
+
+    #[test]
+    fn test_trig_funcs() {
+        // Auto-generated using kalk/scripts/generate_funcs_test_cases.py
+        let in_out = vec![
+            (
+                arg as fn(KalkNum) -> KalkNum,
+                (0.3f64, 0f64),
+                (0.0f64, 0.0f64),
+            ),
+            (arg, (0f64, 0.0f64), (0.0f64, 0.0f64)),
+            (arg, (-0.1f64, -0.5f64), (-1.7681919f64, 0.0f64)),
+            (arg, (0.6f64, -0.5f64), (-0.6947383f64, 0.0f64)),
+            (arg, (2.8f64, 0f64), (0.0f64, 0.0f64)),
+            (arg, (-2.6f64, 0f64), (3.1415927f64, 0.0f64)),
+            (arg, (0f64, 0f64), (0.0f64, 0.0f64)),
+            (ceil, (0.2f64, 0f64), (1.0f64, 0.0f64)),
+            (ceil, (0f64, -0.7f64), (0.0f64, 0.0f64)),
+            (ceil, (-0.8f64, -0.3f64), (0.0f64, 0.0f64)),
+            (ceil, (0.5f64, -0.6f64), (1.0f64, 0.0f64)),
+            (ceil, (2.2f64, 0f64), (3.0f64, 0.0f64)),
+            (ceil, (-2.7f64, 0f64), (-2.0f64, 0.0f64)),
+            (ceil, (0f64, 0f64), (0.0f64, 0.0f64)),
+            (exp, (-0.3f64, 0f64), (0.7408182f64, 0.0f64)),
+            (exp, (0f64, -1.0f64), (0.5403023f64, -0.841471f64)),
+            (exp, (0.5f64, 0.8f64), (1.1486752f64, 1.1827202f64)),
+            (exp, (-0.8f64, 0.5f64), (0.3943233f64, 0.2154198f64)),
+            (exp, (2.9f64, 0f64), (18.1741454f64, 0.0f64)),
+            (exp, (-2.0f64, 0f64), (0.1353353f64, 0.0f64)),
+            (exp, (0f64, 0f64), (1.0f64, 0.0f64)),
+            (floor, (-0.8f64, 0f64), (-1.0f64, 0.0f64)),
+            (floor, (0f64, 0.4f64), (0.0f64, 0.0f64)),
+            (floor, (0.1f64, 0.8f64), (0.0f64, 0.0f64)),
+            (floor, (0.6f64, -0.4f64), (0.0f64, -1.0f64)),
+            (floor, (1.8f64, 0f64), (1.0f64, 0.0f64)),
+            (floor, (-1.8f64, 0f64), (-2.0f64, 0.0f64)),
+            (floor, (0f64, 0f64), (0.0f64, 0.0f64)),
+            (log, (0.4f64, 0f64), (-0.39794f64, 0.0f64)),
+            (log, (0f64, -0.6f64), (-0.2218487f64, -0.6821882f64)),
+            (log, (0.6f64, 0.1f64), (-0.2158991f64, 0.0717232f64)),
+            (log, (-0.7f64, -0.8f64), (0.0265392f64, -0.9943721f64)),
+            (log, (2.2f64, 0f64), (0.3424227f64, 0.0f64)),
+            (log, (-2.9f64, 0f64), (0.462398f64, 1.3643764f64)),
+            (log, (0f64, 0f64), (f64::NEG_INFINITY, 0.0f64)),
+            (ln, (0.3f64, 0f64), (-1.2039728f64, 0.0f64)),
+            (ln, (0f64, 0.0f64), (f64::NEG_INFINITY, 0.0f64)),
+            (ln, (-1.0f64, 0.8f64), (0.2473481f64, 2.4668517f64)),
+            (ln, (-0.2f64, 1.0f64), (0.0196104f64, 1.7681919f64)),
+            (ln, (1.5f64, 0f64), (0.4054651f64, 0.0f64)),
+            (ln, (-2.4f64, 0f64), (0.8754687f64, 3.1415927f64)),
+            (ln, (0f64, 0f64), (f64::NEG_INFINITY, 0.0f64)),
+            (sqrt, (-0.9f64, 0f64), (0.0f64, 0.9486833f64)),
+            (sqrt, (0f64, 0.3f64), (0.3872983f64, 0.3872983f64)),
+            (sqrt, (0.6f64, -0.2f64), (0.7850018f64, -0.1273882f64)),
+            (sqrt, (0.0f64, 0.4f64), (0.4472136f64, 0.4472136f64)),
+            (sqrt, (2.5f64, 0f64), (1.5811388f64, 0.0f64)),
+            (sqrt, (-2.5f64, 0f64), (0.0f64, 1.5811388f64)),
+            (sqrt, (0f64, 0f64), (0.0f64, 0.0f64)),
+            (acos, (-0.8f64, 0f64), (2.4980915f64, 0.0f64)),
+            (acos, (0f64, 0.4f64), (1.5707963f64, -0.3900353f64)),
+            (acos, (-0.5f64, 0.9f64), (1.9389155f64, -0.8561366f64)),
+            (acos, (0.4f64, -1.0f64), (1.2899829f64, 0.9099081f64)),
+            (acos, (2.2f64, 0f64), (0.0f64, 1.4254169f64)),
+            (acos, (-1.5f64, 0f64), (3.1415927f64, -0.9624237f64)),
+            (acos, (0f64, 0f64), (1.5707963f64, 0.0f64)),
+            (acosh, (0.6f64, 0f64), (0.0f64, 0.9272952f64)),
+            (acosh, (0f64, 0.5f64), (0.4812118f64, 1.5707963f64)),
+            (acosh, (1.0f64, -1.0f64), (1.0612751f64, -0.9045569f64)),
+            (acosh, (0.5f64, 0.6f64), (0.6197743f64, 1.1403656f64)),
+            (acosh, (2.2f64, 0f64), (1.4254169f64, 0.0f64)),
+            (acosh, (-2.7f64, 0f64), (1.6501935f64, 3.1415927f64)),
+            (acosh, (0f64, 0f64), (0.0f64, 1.5707963f64)),
+            (acsc, (-0.9f64, 0f64), (-1.5707963f64, 0.4671453f64)),
+            (acsc, (0f64, -0.9f64), (0.0f64, 0.9578004f64)),
+            (acsc, (0.8f64, -0.6f64), (0.6847192f64, 0.7127085f64)),
+            (acsc, (0.3f64, -0.5f64), (0.4742891f64, 1.2767722f64)),
+            (acsc, (2.7f64, 0f64), (0.3794077f64, 0.0f64)),
+            (acsc, (-1.7f64, 0f64), (-0.6288749f64, 0.0f64)),
+            (acsc, (0f64, 0f64), (f64::NAN, f64::NAN)),
+            (acsch, (-0.8f64, 0f64), (-1.047593f64, 0.0f64)),
+            (acsch, (0f64, 0.4f64), (-1.5667992f64, -1.5707963f64)),
+            (acsch, (-0.1f64, -0.9f64), (-0.5019389f64, 1.335583f64)),
+            (acsch, (1.0f64, -0.7f64), (0.6735491f64, 0.3900529f64)),
+            (acsch, (2.5f64, 0f64), (0.3900353f64, 0.0f64)),
+            (acsch, (-2.4f64, 0f64), (-0.4054651f64, 0.0f64)),
+            (acsch, (0f64, 0f64), (f64::NAN, f64::NAN)),
+            (acot, (-1.0f64, 0f64), (-0.7853982f64, 0.0f64)),
+            (acot, (0f64, -0.5f64), (1.5707963f64, 0.5493061f64)),
+            (acot, (-0.4f64, -0.4f64), (-1.1376452f64, 0.3513356f64)),
+            (acot, (-0.9f64, -0.7f64), (-0.7028238f64, 0.3534233f64)),
+            (acot, (2.3f64, 0f64), (0.4101273f64, 0.0f64)),
+            (acot, (-1.7f64, 0f64), (-0.5317241f64, 0.0f64)),
+            (acot, (0f64, 0f64), (1.5707963f64, 0.0f64)),
+            (acoth, (0.5f64, 0f64), (0.5493061f64, -1.5707963f64)),
+            (acoth, (0f64, 0.9f64), (0.0f64, -0.8379812f64)),
+            (acoth, (-0.4f64, -0.1f64), (-0.4180715f64, 1.4525683f64)),
+            (acoth, (-0.9f64, -0.5f64), (-0.6744352f64, 0.7554341f64)),
+            (acoth, (1.7f64, 0f64), (0.6749634f64, 0.0f64)),
+            (acoth, (-2.1f64, 0f64), (-0.518046f64, 0.0f64)),
+            (acoth, (0f64, 0f64), (0.0f64, 1.5707963f64)),
+            (asec, (-0.1f64, 0f64), (3.1415927f64, -2.9932228f64)),
+            (asec, (0f64, 0.7f64), (1.5707963f64, 1.1544774f64)),
+            (asec, (0.9f64, -0.4f64), (0.6818568f64, -0.6148366f64)),
+            (asec, (-0.5f64, 0.9f64), (1.9278638f64, 0.8134796f64)),
+            (asec, (1.5f64, 0f64), (0.8410687f64, 0.0f64)),
+            (asec, (-2.7f64, 0f64), (1.950204f64, 0.0f64)),
+            (asec, (0f64, 0f64), (f64::NAN, f64::NAN)),
+            (asech, (0.6f64, 0f64), (1.0986123f64, 0.0f64)),
+            (asech, (0f64, -1.0f64), (0.8813736f64, 1.5707963f64)),
+            (asech, (0.1f64, -0.7f64), (1.1434743f64, 1.4548078f64)),
+            (asech, (-0.4f64, -0.3f64), (1.3742673f64, 2.4355905f64)),
+            (asech, (2.3f64, 0f64), (0.0f64, 1.1209995f64)),
+            (asech, (-2.2f64, 0f64), (0.0f64, 2.0426582f64)),
+            (asech, (0f64, 0f64), (f64::NAN, f64::NAN)),
+            (asin, (-0.8f64, 0f64), (-0.9272952f64, 0.0f64)),
+            (asin, (0f64, 0.5f64), (0.0f64, 0.4812118f64)),
+            (asin, (-0.2f64, -1.0f64), (-0.1411811f64, -0.8884618f64)),
+            (asin, (-0.8f64, 0.3f64), (-0.8214537f64, 0.427304f64)),
+            (asin, (1.5f64, 0f64), (1.5707963f64, -0.9624237f64)),
+            (asin, (-3.0f64, 0f64), (-1.5707963f64, 1.7627472f64)),
+            (asin, (0f64, 0f64), (0.0f64, 0.0f64)),
+            (asinh, (1.0f64, 0f64), (0.8813736f64, 0.0f64)),
+            (asinh, (0f64, 0.1f64), (0.0f64, 0.1001674f64)),
+            (asinh, (0.9f64, 1.0f64), (1.0029766f64, 0.7031f64)),
+            (asinh, (-0.5f64, 0.8f64), (-0.627368f64, 0.7272513f64)),
+            (asinh, (1.8f64, 0f64), (1.3504407f64, 0.0f64)),
+            (asinh, (-2.4f64, 0f64), (-1.6094379f64, 0.0f64)),
+            (asinh, (0f64, 0f64), (0.0f64, 0.0f64)),
+            (atan, (0.0f64, 0f64), (0.0f64, 0.0f64)),
+            (atan, (0f64, 0.8f64), (0.0f64, 1.0986123f64)),
+            (atan, (0.4f64, 0.2f64), (0.3926991f64, 0.1732868f64)),
+            (atan, (0.4f64, -0.3f64), (0.4088225f64, -0.2614921f64)),
+            (atan, (1.5f64, 0f64), (0.9827937f64, 0.0f64)),
+            (atan, (-1.8f64, 0f64), (-1.0636978f64, 0.0f64)),
+            (atan, (0f64, 0f64), (0.0f64, 0.0f64)),
+            (atanh, (0.9f64, 0f64), (1.4722195f64, 0.0f64)),
+            (atanh, (0f64, -0.1f64), (0.0f64, -0.0996687f64)),
+            (atanh, (-1.0f64, -0.3f64), (-0.9541226f64, -0.8598431f64)),
+            (atanh, (0.6f64, -0.4f64), (0.5350165f64, -0.5151884f64)),
+            (atanh, (1.5f64, 0f64), (0.804719f64, -1.5707963f64)),
+            (atanh, (-2.3f64, 0f64), (-0.4657791f64, 1.5707963f64)),
+            (atanh, (0f64, 0f64), (0.0f64, 0.0f64)),
+            (cos, (0.1f64, 0f64), (0.9950042f64, 0.0f64)),
+            (cos, (0f64, -0.2f64), (1.0200668f64, 0.0f64)),
+            (cos, (-0.1f64, -0.1f64), (0.9999833f64, -0.01f64)),
+            (cos, (0.5f64, -0.4f64), (0.9487303f64, 0.1969252f64)),
+            (cos, (2.4f64, 0f64), (-0.7373937f64, 0.0f64)),
+            (cos, (-2.2f64, 0f64), (-0.5885011f64, 0.0f64)),
+            (cos, (0f64, 0f64), (1.0f64, 0.0f64)),
+            (cosh, (0.0f64, 0f64), (1.0f64, 0.0f64)),
+            (cosh, (0f64, 0.9f64), (0.62161f64, 0.0f64)),
+            (cosh, (0.8f64, -0.4f64), (1.2318592f64, -0.3458448f64)),
+            (cosh, (-0.2f64, 1.0f64), (0.5511444f64, -0.1694184f64)),
+            (cosh, (2.9f64, 0f64), (9.1145843f64, 0.0f64)),
+            (cosh, (-2.7f64, 0f64), (7.4734686f64, 0.0f64)),
+            (cosh, (0f64, 0f64), (1.0f64, 0.0f64)),
+            (csc, (0.5f64, 0f64), (2.0858296f64, 0.0f64)),
+            (csc, (0f64, -0.6f64), (0.0f64, 1.5707129f64)),
+            (csc, (-0.9f64, -0.7f64), (-0.8268848f64, 0.3965713f64)),
+            (csc, (0.3f64, -0.5f64), (0.9285645f64, 1.3871816f64)),
+            (csc, (2.3f64, 0f64), (1.3410125f64, 0.0f64)),
+            (csc, (-2.5f64, 0f64), (-1.6709215f64, 0.0f64)),
+            (csc, (0f64, 0f64), (f64::NAN, f64::NAN)),
+            (csch, (-0.8f64, 0f64), (-1.1259917f64, 0.0f64)),
+            (csch, (0f64, 0.7f64), (0.0f64, -1.5522703f64)),
+            (csch, (0.6f64, -0.4f64), (1.0528253f64, 0.8288386f64)),
+            (csch, (-0.4f64, 0.0f64), (-2.4345571f64, 0.0f64)),
+            (csch, (2.7f64, 0f64), (0.1350209f64, 0.0f64)),
+            (csch, (-3.0f64, 0f64), (-0.0998216f64, 0.0f64)),
+            (csch, (0f64, 0f64), (f64::NAN, f64::NAN)),
+            (cot, (-0.3f64, 0f64), (-3.2327281f64, 0.0f64)),
+            (cot, (0f64, 0.4f64), (0.0f64, -2.6319324f64)),
+            (cot, (-0.9f64, 0.4f64), (-0.6224112f64, -0.5676115f64)),
+            (cot, (-0.2f64, 0.8f64), (-0.2350987f64, -1.4341723f64)),
+            (cot, (1.7f64, 0f64), (-0.1299275f64, 0.0f64)),
+            (cot, (-1.8f64, 0f64), (0.2333035f64, 0.0f64)),
+            (cot, (0f64, 0f64), (f64::NAN, f64::NAN)),
+            (coth, (0.3f64, 0f64), (3.4327384f64, 0.0f64)),
+            (coth, (0f64, 0.9f64), (0.0f64, -0.7935511f64)),
+            (coth, (-0.7f64, -0.5f64), (-1.1823582f64, 0.5224593f64)),
+            (coth, (-0.8f64, -0.3f64), (-1.3558181f64, 0.3222608f64)),
+            (coth, (2.8f64, 0f64), (1.0074232f64, 0.0f64)),
+            (coth, (-2.3f64, 0f64), (-1.0203078f64, 0.0f64)),
+            (coth, (0f64, 0f64), (f64::NAN, f64::NAN)),
+            (sec, (0.4f64, 0f64), (1.0857044f64, 0.0f64)),
+            (sec, (0f64, -0.7f64), (0.7967055f64, 0.0f64)),
+            (sec, (0.7f64, -0.2f64), (1.2472669f64, -0.2073543f64)),
+            (sec, (0.0f64, 0.1f64), (0.9950207f64, 0.0f64)),
+            (sec, (1.5f64, 0f64), (14.1368329f64, 0.0f64)),
+            (sec, (-1.6f64, 0f64), (-34.2471356f64, 0.0f64)),
+            (sec, (0f64, 0f64), (1.0f64, 0.0f64)),
+            (sech, (-0.6f64, 0f64), (0.8435507f64, 0.0f64)),
+            (sech, (0f64, 1.0f64), (1.8508157f64, 0.0f64)),
+            (sech, (0.5f64, -0.9f64), (1.0653621f64, 0.6204037f64)),
+            (sech, (-0.8f64, 0.9f64), (0.7074639f64, 0.5919997f64)),
+            (sech, (2.0f64, 0f64), (0.2658022f64, 0.0f64)),
+            (sech, (-2.0f64, 0f64), (0.2658022f64, 0.0f64)),
+            (sech, (0f64, 0f64), (1.0f64, 0.0f64)),
+            (sin, (1.0f64, 0f64), (0.841471f64, 0.0f64)),
+            (sin, (0f64, -0.3f64), (0.0f64, -0.3045203f64)),
+            (sin, (-0.1f64, -0.6f64), (-0.118349f64, -0.633473f64)),
+            (sin, (-0.4f64, 0.4f64), (-0.4209894f64, 0.3783279f64)),
+            (sin, (2.8f64, 0f64), (0.3349882f64, 0.0f64)),
+            (sin, (-2.0f64, 0f64), (-0.9092974f64, 0.0f64)),
+            (sin, (0f64, 0f64), (0.0f64, 0.0f64)),
+            (sinh, (-0.4f64, 0f64), (-0.4107523f64, 0.0f64)),
+            (sinh, (0f64, -1.0f64), (0.0f64, -0.841471f64)),
+            (sinh, (-0.9f64, -0.4f64), (-0.9454845f64, -0.5580701f64)),
+            (sinh, (0.0f64, 0.9f64), (0.0f64, 0.7833269f64)),
+            (sinh, (2.7f64, 0f64), (7.4062631f64, 0.0f64)),
+            (sinh, (-1.9f64, 0f64), (-3.2681629f64, 0.0f64)),
+            (sinh, (0f64, 0f64), (0.0f64, 0.0f64)),
+            (tan, (-0.6f64, 0f64), (-0.6841368f64, 0.0f64)),
+            (tan, (0f64, -0.9f64), (0.0f64, -0.7162979f64)),
+            (tan, (-0.1f64, 0.1f64), (-0.099328f64, 0.1006613f64)),
+            (tan, (0.7f64, -0.1f64), (0.8280854f64, -0.1691851f64)),
+            (tan, (2.8f64, 0f64), (-0.3555298f64, 0.0f64)),
+            (tan, (-1.6f64, 0f64), (34.2325327f64, 0.0f64)),
+            (tan, (0f64, 0f64), (0.0f64, 0.0f64)),
+            (tanh, (-0.4f64, 0f64), (-0.379949f64, 0.0f64)),
+            (tanh, (0f64, -0.3f64), (0.0f64, -0.3093362f64)),
+            (tanh, (-0.8f64, 0.5f64), (-0.7619454f64, 0.2698954f64)),
+            (tanh, (-0.3f64, 0.0f64), (-0.2913126f64, 0.0f64)),
+            (tanh, (1.5f64, 0f64), (0.9051483f64, 0.0f64)),
+            (tanh, (-2.3f64, 0f64), (-0.9800964f64, 0.0f64)),
+            (tanh, (0f64, 0f64), (0.0f64, 0.0f64)),
+        ];
+
+        for (i, (func, input, expected_output)) in in_out.iter().enumerate() {
+            let actual_output = func(KalkNum::new_with_imaginary(
+                KalkNum::from(input.0).value,
+                "",
+                KalkNum::from(input.1).value,
+            ));
+
+            let expected_has_nan_or_inf = expected_output.0.is_nan()
+                || expected_output.0.is_infinite()
+                || expected_output.1.is_nan()
+                || expected_output.1.is_infinite();
+            let actual_has_nan_or_inf = actual_output.to_f64().is_nan()
+                || actual_output.to_f64().is_infinite()
+                || actual_output.imaginary_to_f64().is_nan()
+                || actual_output.imaginary_to_f64().is_infinite();
+
+            if expected_has_nan_or_inf || actual_has_nan_or_inf {
+                assert!(true);
+                continue;
+            }
+
+            println!(
+                "{} | expected: {}, {}",
+                i, expected_output.0, expected_output.1
+            );
+            println!(
+                "{} | got: {}, {}",
+                i,
+                actual_output.to_f64(),
+                actual_output.imaginary_to_f64()
+            );
+            assert!(cmp(expected_output.0, actual_output.to_f64()));
+            assert!(cmp(expected_output.1, actual_output.imaginary_to_f64()));
+        }
+    }
+}
diff --git a/kalk/src/prelude/with_rug.rs b/kalk/src/prelude/with_rug.rs
index 1adf48a..4a2f3ab 100644
--- a/kalk/src/prelude/with_rug.rs
+++ b/kalk/src/prelude/with_rug.rs
@@ -11,7 +11,6 @@ pub(crate) mod funcs {
     use crate::prelude::funcs::abs;
 
     pub fn arg(x: KalkNum) -> KalkNum {
-        // i(ln|x| - ln(x))
         KalkNum::new(x.imaginary_value.atan2(&x.value), &x.unit)
     }
 
diff --git a/kalk/src/test_helpers.rs b/kalk/src/test_helpers.rs
index 48e470e..1111e11 100755
--- a/kalk/src/test_helpers.rs
+++ b/kalk/src/test_helpers.rs
@@ -13,6 +13,10 @@ pub fn token(kind: TokenKind, value: &str) -> Token {
     }
 }
 
+pub fn cmp(x: f64, y: f64) -> bool {
+    (x - y).abs() < 0.0001
+}
+
 pub fn literal(value: f64) -> Box<Expr> {
     Box::new(Expr::Literal(value))
 }