doc: add missing examples for multiple math functions (#17018)

* Update Scalar_functions.md

* pretier fix

* Updated files

* Updated Scalar functions

* Update datafusion/functions/src/math/log.rs

Co-authored-by: Jeffrey Vo <[email protected]>

* Update datafusion/functions/src/math/monotonicity.rs

Co-authored-by: Jeffrey Vo <[email protected]>

* Update datafusion/functions/src/math/monotonicity.rs

Co-authored-by: Jeffrey Vo <[email protected]>

* Update datafusion/functions/src/math/nans.rs

Co-authored-by: Jeffrey Vo <[email protected]>

* Update datafusion/functions/src/math/nanvl.rs

Co-authored-by: Jeffrey Vo <[email protected]>

* Fix tanh example to be tanh not trunc

* Run update_function_docs.sh

---------

Co-authored-by: Jeffrey Vo <[email protected]>

Author: Adez017

datafusion/functions/src/math/abs.rs

@@ -108,6 +108,14 @@ fn create_abs_function(input_data_type: &DataType) -> Result<MathArrayFunction>
     doc_section(label = "Math Functions"),
     description = "Returns the absolute value of a number.",
     syntax_example = "abs(numeric_expression)",
+    sql_example = r#"```sql
+> SELECT abs(-5);
++----------+
+| abs(-5)  |
++----------+
+| 5        |
++----------+
+```"#,
     standard_argument(name = "numeric_expression", prefix = "Numeric")
 )]
 #[derive(Debug, PartialEq, Eq, Hash)]

datafusion/functions/src/math/cot.rs

@@ -32,6 +32,14 @@ use datafusion_macros::user_doc;
     doc_section(label = "Math Functions"),
     description = "Returns the cotangent of a number.",
     syntax_example = r#"cot(numeric_expression)"#,
+    sql_example = r#"```sql
+> SELECT cot(1);
++---------+
+| cot(1)  |
++---------+
+| 0.64209 |
++---------+
+```"#,
     standard_argument(name = "numeric_expression", prefix = "Numeric")
 )]
 #[derive(Debug, PartialEq, Eq, Hash)]

datafusion/functions/src/math/factorial.rs

@@ -37,6 +37,14 @@ use datafusion_macros::user_doc;
     doc_section(label = "Math Functions"),
     description = "Factorial. Returns 1 if value is less than 2.",
     syntax_example = "factorial(numeric_expression)",
+    sql_example = r#"```sql
+> SELECT factorial(5);
++---------------+
+| factorial(5)  |
++---------------+
+| 120           |
++---------------+
+```"#,
     standard_argument(name = "numeric_expression", prefix = "Numeric")
 )]
 #[derive(Debug, PartialEq, Eq, Hash)]

datafusion/functions/src/math/gcd.rs

@@ -34,6 +34,14 @@ use datafusion_macros::user_doc;
     doc_section(label = "Math Functions"),
     description = "Returns the greatest common divisor of `expression_x` and `expression_y`. Returns 0 if both inputs are zero.",
     syntax_example = "gcd(expression_x, expression_y)",
+    sql_example = r#"```sql
+> SELECT gcd(48, 18);
++------------+
+| gcd(48,18) |
++------------+
+| 6          |
++------------+
+```"#,
     standard_argument(name = "expression_x", prefix = "First numeric"),
     standard_argument(name = "expression_y", prefix = "Second numeric")
 )]

datafusion/functions/src/math/iszero.rs

@@ -36,6 +36,14 @@ use crate::utils::make_scalar_function;
     doc_section(label = "Math Functions"),
     description = "Returns true if a given number is +0.0 or -0.0 otherwise returns false.",
     syntax_example = "iszero(numeric_expression)",
+    sql_example = r#"```sql
+> SELECT iszero(0);
++------------+
+| iszero(0)  |
++------------+
+| true       |
++------------+
+```"#,
     standard_argument(name = "numeric_expression", prefix = "Numeric")
 )]
 #[derive(Debug, PartialEq, Eq, Hash)]

datafusion/functions/src/math/lcm.rs

@@ -37,6 +37,14 @@ use crate::utils::make_scalar_function;
     doc_section(label = "Math Functions"),
     description = "Returns the least common multiple of `expression_x` and `expression_y`. Returns 0 if either input is zero.",
     syntax_example = "lcm(expression_x, expression_y)",
+    sql_example = r#"```sql
+> SELECT lcm(4, 5);
++----------+
+| lcm(4,5) |
++----------+
+| 20       |
++----------+
+```"#,
     standard_argument(name = "expression_x", prefix = "First numeric"),
     standard_argument(name = "expression_y", prefix = "Second numeric")
 )]

datafusion/functions/src/math/log.rs

@@ -48,6 +48,14 @@ use datafusion_macros::user_doc;
     description = "Returns the base-x logarithm of a number. Can either provide a specified base, or if omitted then takes the base-10 of a number.",
     syntax_example = r#"log(base, numeric_expression)
 log(numeric_expression)"#,
+    sql_example = r#"```sql
+> SELECT log(10);
++---------+
+| log(10) |
++---------+
+| 1.0     |
++---------+
+```"#,
     standard_argument(name = "base", prefix = "Base numeric"),
     standard_argument(name = "numeric_expression", prefix = "Numeric")
 )]