BrianHung · BrianHung · Aug 1, 2025 · Aug 1, 2025 · Aug 1, 2025
diff --git a/base/src/expressions/parser/static_analysis.rs b/base/src/expressions/parser/static_analysis.rs
@@ -785,6 +785,8 @@ fn get_function_args_signature(kind: &Function, arg_count: usize) -> Vec<Signatu
         Function::Formulatext => args_signature_scalars(arg_count, 1, 0),
         Function::Unicode => args_signature_scalars(arg_count, 1, 0),
         Function::Geomean => vec![Signature::Vector; arg_count],
+        Function::Gauss | Function::Phi => args_signature_scalars(arg_count, 1, 0),
+        Function::Standardize => args_signature_scalars(arg_count, 3, 0),
     }
 }
 
@@ -990,5 +992,6 @@ fn static_analysis_on_function(kind: &Function, args: &[Node]) -> StaticResult {
         Function::Eomonth => scalar_arguments(args),
         Function::Formulatext => not_implemented(args),
         Function::Geomean => not_implemented(args),
+        Function::Gauss | Function::Phi | Function::Standardize => scalar_arguments(args),
     }
 }
diff --git a/base/src/functions/engineering/mod.rs b/base/src/functions/engineering/mod.rs
@@ -4,4 +4,4 @@ mod complex;
 mod convert;
 mod misc;
 mod number_basis;
-mod transcendental;
+pub(crate) mod transcendental;
diff --git a/base/src/functions/mod.rs b/base/src/functions/mod.rs
@@ -145,6 +145,9 @@ pub enum Function {
     Maxifs,
     Minifs,
     Geomean,
+    Gauss,
+    Phi,
+    Standardize,
 
     // Date and time
     Date,
@@ -253,7 +256,7 @@ pub enum Function {
 }
 
 impl Function {
-    pub fn into_iter() -> IntoIter<Function, 198> {
+    pub fn into_iter() -> IntoIter<Function, 201> {
         [
             Function::And,
             Function::False,
@@ -357,6 +360,9 @@ impl Function {
             Function::Maxifs,
             Function::Minifs,
             Function::Geomean,
+            Function::Gauss,
+            Function::Phi,
+            Function::Standardize,
             Function::Year,
             Function::Day,
             Function::Month,
@@ -625,6 +631,9 @@ impl Function {
             "MAXIFS" | "_XLFN.MAXIFS" => Some(Function::Maxifs),
             "MINIFS" | "_XLFN.MINIFS" => Some(Function::Minifs),
             "GEOMEAN" => Some(Function::Geomean),
+            "GAUSS" => Some(Function::Gauss),
+            "PHI" => Some(Function::Phi),
+            "STANDARDIZE" => Some(Function::Standardize),
             // Date and Time
             "YEAR" => Some(Function::Year),
             "DAY" => Some(Function::Day),
@@ -836,6 +845,9 @@ impl fmt::Display for Function {
             Function::Maxifs => write!(f, "MAXIFS"),
             Function::Minifs => write!(f, "MINIFS"),
             Function::Geomean => write!(f, "GEOMEAN"),
+            Function::Gauss => write!(f, "GAUSS"),
+            Function::Phi => write!(f, "PHI"),
+            Function::Standardize => write!(f, "STANDARDIZE"),
             Function::Year => write!(f, "YEAR"),
             Function::Day => write!(f, "DAY"),
             Function::Month => write!(f, "MONTH"),
@@ -1076,6 +1088,9 @@ impl Model {
             Function::Maxifs => self.fn_maxifs(args, cell),
             Function::Minifs => self.fn_minifs(args, cell),
             Function::Geomean => self.fn_geomean(args, cell),
+            Function::Gauss => self.fn_gauss(args, cell),
+            Function::Phi => self.fn_phi(args, cell),
+            Function::Standardize => self.fn_standardize(args, cell),
             // Date and Time
             Function::Year => self.fn_year(args, cell),
             Function::Day => self.fn_day(args, cell),

diff --git a/base/src/functions/statistical.rs b/base/src/functions/statistical.rs
@@ -7,7 +7,9 @@ use crate::{
     model::Model,
 };
 
+use super::engineering::transcendental::erf;
 use super::util::build_criteria;
+use std::f64::consts::PI;
 
 impl Model {
     pub(crate) fn fn_average(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
@@ -730,4 +732,72 @@ impl Model {
         }
         CalcResult::Number(product.powf(1.0 / count))
     }
+
+    pub(crate) fn fn_gauss(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 1 {
+            return CalcResult::new_args_number_error(cell);
+        }
+        let z = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(s) => return s,
+        };
+        let result = 0.5 * erf(z / std::f64::consts::SQRT_2);
+        if result.is_nan() || result.is_infinite() {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "Invalid parameter for GAUSS function".to_string(),
+            );
+        }
+        CalcResult::Number(result)
+    }
+
+    pub(crate) fn fn_phi(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 1 {
+            return CalcResult::new_args_number_error(cell);
+        }
+        let x = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(s) => return s,
+        };
+        let result = (1.0 / (2.0 * PI).sqrt()) * f64::exp(-0.5 * x * x);
+        if result.is_nan() || result.is_infinite() {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "Invalid parameter for PHI function".to_string(),
+            );
+        }
+        CalcResult::Number(result)
+    }
+
+    pub(crate) fn fn_standardize(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 3 {
+            return CalcResult::new_args_number_error(cell);
+        }
+        let x = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(s) => return s,
+        };
+        let mean = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f,
+            Err(s) => return s,
+        };
+        let std_dev = match self.get_number_no_bools(&args[2], cell) {
+            Ok(f) => f,
+            Err(s) => return s,
+        };
+        if std_dev <= 0.0 {
+            return CalcResult::new_error(Error::NUM, cell, "standard_dev must be > 0".to_string());
+        }
+        let result = (x - mean) / std_dev;
+        if result.is_nan() || result.is_infinite() {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "Invalid parameter for STANDARDIZE function".to_string(),
+            );
+        }
+        CalcResult::Number(result)
+    }
 }
diff --git a/base/src/test/mod.rs b/base/src/test/mod.rs
@@ -64,6 +64,7 @@ mod test_issue_155;
 mod test_ln;
 mod test_log;
 mod test_log10;
+mod test_normal_distribution;
 mod test_percentage;
 mod test_set_functions_error_handling;
 mod test_today;

diff --git a/base/src/test/test_normal_distribution.rs b/base/src/test/test_normal_distribution.rs
@@ -0,0 +1,119 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn test_gauss() {
+    let mut model = new_empty_model();
+    model._set("A1", "=GAUSS(2)");
+    model._set("A2", "=GAUSS(0)");
+    model._set("A3", "=GAUSS(-1)");
+    model.evaluate();
+    let a1: f64 = model._get_text("A1").parse().unwrap();
+    let a2: f64 = model._get_text("A2").parse().unwrap();
+    let a3: f64 = model._get_text("A3").parse().unwrap();
+    assert!((a1 - 0.477249868).abs() < 1e-9);
+    assert!(a2.abs() < 1e-12);
+    assert!((a3 - (-0.341344746)).abs() < 1e-9);
+}
+
+#[test]
+fn test_phi() {
+    let mut model = new_empty_model();
+    model._set("A1", "=PHI(0)");
+    model._set("A2", "=PHI(1)");
+    model._set("A3", "=PHI(-1)");
+    model.evaluate();
+    assert_eq!(model._get_text("A1"), *"0.39894228");
+    assert_eq!(model._get_text("A2"), *"0.241970725");
+    assert_eq!(model._get_text("A3"), *"0.241970725"); // PHI is symmetric around 0
+}
+
+#[test]
+fn test_standardize() {
+    let mut model = new_empty_model();
+    model._set("A1", "=STANDARDIZE(75,70,5)");
+    model._set("A2", "=STANDARDIZE(65,70,5)");
+    model._set("A3", "=STANDARDIZE(70,70,5)");
+    model._set("A4", "=STANDARDIZE(80,70,10)");
+    model.evaluate();
+    assert_eq!(model._get_text("A1"), *"1");
+    assert_eq!(model._get_text("A2"), *"-1");
+    assert_eq!(model._get_text("A3"), *"0");
+    assert_eq!(model._get_text("A4"), *"1");
+}
+
+#[test]
+fn test_gauss_phi_standardize_errors() {
+    let mut model = new_empty_model();
+
+    // Test wrong argument counts
+    model._set("B1", "=GAUSS()"); // Too few arguments
+    model._set("B2", "=GAUSS(1,2)"); // Too many arguments
+    model._set("B3", "=PHI()"); // Too few arguments
+    model._set("B4", "=PHI(1,2)"); // Too many arguments
+    model._set("B5", "=STANDARDIZE(1,2)"); // Too few arguments
+    model._set("B6", "=STANDARDIZE(1,2,3,4)"); // Too many arguments
+
+    // Test invalid standard deviation
+    model._set("B7", "=STANDARDIZE(1,2,0)"); // Zero std dev
+    model._set("B8", "=STANDARDIZE(1,2,-1)"); // Negative std dev
+
+    model.evaluate();
+
+    // All should return errors
+    assert_eq!(model._get_text("B1"), *"#ERROR!");
+    assert_eq!(model._get_text("B2"), *"#ERROR!");
+    assert_eq!(model._get_text("B3"), *"#ERROR!");
+    assert_eq!(model._get_text("B4"), *"#ERROR!");
+    assert_eq!(model._get_text("B5"), *"#ERROR!");
+    assert_eq!(model._get_text("B6"), *"#ERROR!");
+    assert_eq!(model._get_text("B7"), *"#NUM!"); // Should be NUM error for invalid std dev
+    assert_eq!(model._get_text("B8"), *"#NUM!"); // Should be NUM error for invalid std dev
+}
+
+#[test]
+fn test_extreme_values() {
+    let mut model = new_empty_model();
+
+    // Test with very large values that shouldn't cause NaN/infinity
+    model._set("C1", "=GAUSS(100)"); // Very large positive value
+    model._set("C2", "=GAUSS(-100)"); // Very large negative value
+    model._set("C3", "=PHI(10)"); // Should be very small but valid
+    model._set("C4", "=PHI(-10)"); // Should be very small but valid
+
+    model.evaluate();
+
+    // These should all produce valid numbers, not errors
+    assert_ne!(model._get_text("C1"), *"#NUM!");
+    assert_ne!(model._get_text("C2"), *"#NUM!");
+    assert_ne!(model._get_text("C3"), *"#NUM!");
+    assert_ne!(model._get_text("C4"), *"#NUM!");
+
+    // Verify GAUSS approaches limits correctly
+    let c1: f64 = model._get_text("C1").parse().unwrap();
+    let c2: f64 = model._get_text("C2").parse().unwrap();
+    assert!(c1 > 0.49); // Should approach 0.5 for large positive values
+    assert!(c2 < -0.49); // Should approach -0.5 for large negative values
+}
+
+#[test]
+fn test_type_errors() {
+    let mut model = new_empty_model();
+
+    // Test with text inputs
+    model._set("D1", "=GAUSS(\"text\")");
+    model._set("D2", "=PHI(\"text\")");
+    model._set("D3", "=STANDARDIZE(\"text\",70,5)");
+    model._set("D4", "=STANDARDIZE(75,\"text\",5)");
+    model._set("D5", "=STANDARDIZE(75,70,\"text\")");
+
+    model.evaluate();
+
+    // All should return VALUE errors
+    assert_eq!(model._get_text("D1"), *"#VALUE!");
+    assert_eq!(model._get_text("D2"), *"#VALUE!");
+    assert_eq!(model._get_text("D3"), *"#VALUE!");
+    assert_eq!(model._get_text("D4"), *"#VALUE!");
+    assert_eq!(model._get_text("D5"), *"#VALUE!");
+}
diff --git a/docs/src/functions/statistical.md b/docs/src/functions/statistical.md
@@ -57,7 +57,7 @@ You can track the progress in this [GitHub issue](https://github.com/ironcalc/Ir
 | GAMMA.INV                | <Badge type="info" text="Not implemented yet" /> | –             |
 | GAMMALN                  | <Badge type="info" text="Not implemented yet" /> | –             |
 | GAMMALN.PRECISE          | <Badge type="info" text="Not implemented yet" /> | –             |
-| GAUSS                    | <Badge type="info" text="Not implemented yet" /> | –             |
+| GAUSS                    | <Badge type="tip" text="Available" />            | –             |
 | GEOMEAN                  | <Badge type="info" text="Available" />            | –             |
 | GROWTH                   | <Badge type="info" text="Not implemented yet" /> | –             |
 | HARMEAN                  | <Badge type="info" text="Not implemented yet" /> | –             |
@@ -87,7 +87,7 @@ You can track the progress in this [GitHub issue](https://github.com/ironcalc/Ir
 | PERCENTRANK.INC          | <Badge type="info" text="Not implemented yet" /> | –             |
 | PERMUT                   | <Badge type="info" text="Not implemented yet" /> | –             |
 | PERMUTATIONA             | <Badge type="info" text="Not implemented yet" /> | –             |
-| PHI                      | <Badge type="info" text="Not implemented yet" /> | –             |
+| PHI                      | <Badge type="tip" text="Available" />            | –             |
 | POISSON.DIST             | <Badge type="info" text="Not implemented yet" /> | –             |
 | PROB                     | <Badge type="info" text="Not implemented yet" /> | –             |
 | QUARTILE.EXC             | <Badge type="info" text="Not implemented yet" /> | –             |
@@ -99,7 +99,7 @@ You can track the progress in this [GitHub issue](https://github.com/ironcalc/Ir
 | SKEW.P                   | <Badge type="info" text="Not implemented yet" /> | –             |
 | SLOPE                    | <Badge type="info" text="Not implemented yet" /> | –             |
 | SMALL                    | <Badge type="info" text="Not implemented yet" /> | –             |
-| STANDARDIZE              | <Badge type="info" text="Not implemented yet" /> | –             |
+| STANDARDIZE              | <Badge type="tip" text="Available" />            | –             |
 | STDEV.P                  | <Badge type="info" text="Not implemented yet" /> | –             |
 | STDEV.S                  | <Badge type="info" text="Not implemented yet" /> | –             |
 | STDEVA                   | <Badge type="info" text="Not implemented yet" /> | –             |

diff --git a/docs/src/functions/statistical/gauss.md b/docs/src/functions/statistical/gauss.md
@@ -7,6 +7,5 @@ lang: en-US
 # GAUSS
 
 ::: warning
-🚧 This function is not yet available in IronCalc.
-[Follow development here](https://github.com/ironcalc/IronCalc/labels/Functions)
+🚧 This function is implemented but currently lacks detailed documentation. For guidance, you may refer to the equivalent functionality in [Microsoft Excel documentation](https://support.microsoft.com/en-us/office/excel-functions-by-category-5f91f4e9-7b42-46d2-9bd1-63f26a86c0eb).
 :::
diff --git a/docs/src/functions/statistical/phi.md b/docs/src/functions/statistical/phi.md
@@ -7,6 +7,5 @@ lang: en-US
 # PHI
 
 ::: warning
-🚧 This function is not yet available in IronCalc.
-[Follow development here](https://github.com/ironcalc/IronCalc/labels/Functions)
+🚧 This function is implemented but currently lacks detailed documentation. For guidance, you may refer to the equivalent functionality in [Microsoft Excel documentation](https://support.microsoft.com/en-us/office/excel-functions-by-category-5f91f4e9-7b42-46d2-9bd1-63f26a86c0eb).
 :::
diff --git a/docs/src/functions/statistical/standardize.md b/docs/src/functions/statistical/standardize.md
@@ -7,6 +7,5 @@ lang: en-US
 # STANDARDIZE
 
 ::: warning
-🚧 This function is not yet available in IronCalc.
-[Follow development here](https://github.com/ironcalc/IronCalc/labels/Functions)
+🚧 This function is implemented but currently lacks detailed documentation. For guidance, you may refer to the equivalent functionality in [Microsoft Excel documentation](https://support.microsoft.com/en-us/office/excel-functions-by-category-5f91f4e9-7b42-46d2-9bd1-63f26a86c0eb).
 :::