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[[Category: Analytica User Guide]]
[[Category: Functions]]

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Analytica provides a rich set of built-in functions including [[Math functions]], [[Array Functions and Operators|array]], [[Statistical functions|statistical]],  [[Text, Date, Math, and Financial Functions]], [[Probability Distributions]], [[Spreadsheets and Analytica|spreadsheet functions]] and more. You can also write and use your own [[User-defined Functions and Libraries]]).

Here are some simple expressions involving functions.
:<code>[[Exp]](1) &rarr; 2.718281828459</code>
:<code>[[Sqrt]](3^2 + 4^2) &rarr; 5 </code>
:<code>[[Mod]](7, 3) &rarr; 1</code>
:<code>[[Normal]](mean: 500, sdeviation: 100)</code>
:<code>[[FindInText]]('ONE', 'Result is one or two.', caseInsensitive: True, return: 'S') &rarr; 'one'</code>

You can see
==Position-based function calls==
 
With this conventional syntax, you just list the parameters after the function name between parentheses in the same sequence that they are defined for the function:
:<code>FunctionName(param1, param2, ...)</code>

In a function call, each parameter may be a constant, name of a variable, or a more complex expression with operators, or function calls.  In some cases, a parameter must be of an expected type -- for example, the second parameter of Sum must be an index to sum over:
:<code>[[Sum]](Cash_by_year, Year)</code>

Some parameters are [[Optional parameter|optional]], in which case you may omit them and the function will use default values.

== Name-based function calls==

With name-based syntax to call a function, you name each parameter, followed by a colon (:) and the value passed to that parameter.  You may list the parameters in any order, and omit any optional parameters. For example, [[LogNormal]] has four parameters, of which you may provide any two to define the distribution:
:<code>[[LogNormal]](median, gsdev, mean, stddev)</code>

You can call it using name-based syntax:
:<code>[[LogNormal]](mean: 10, stddev: 1.5)</code>

This is equivalent to this position-based syntax, using extra commas to indicate omitted parameters:
:<code>[[LogNormal]]( , , 10, 1.5)</code>

Name-based syntax is useful for functions with many optional parameters, since you don't have to count commas and remember the order of the parameters. It’s usually easier to read name-based function calls.

You may mix position- and named-based syntax if you use position for the initial parameters:
:<code>[[LogNormal]](10, stddev: 4)</code>
You may not  use a position-based parameter after a name-based parameter:
:<code>[[LogNormal]](mean: 10, 1.5) &rarr; ''syntax error'' </code>

==See Also==
<div style="column-count:2;-moz-column-count:2;-webkit-column-count:2">
* [[Using Named Parameters]]
* [[Function Parameter Qualifiers]]
* [[Parameter qualifiers]]
* [[ParameterEnumeration]]
* [[Conventions for parameters and operands]]
* [[Function_parameter_qualifiers#Repeated_parameters_.28....29|Repeated parameters]]
* [[Repeated Parameter Forwarding]]
* [[User-Defined Functions]]
* [[Expression Syntax]]
* [[Expression Assist]]
* [[Procedural Programming Example]]
* [[Summary of Programming Constructs]]
</div>


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