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# symfun

Create symbolic functions

## Syntax

``f(inputs) = formula``
``f = symfun(formula,inputs)``

## Description

example

````f(inputs) = formula` creates the symbolic function `f`. For example, ```f(x,y) = x + y```. The symbolic variables in `inputs` are the input arguments. The symbolic expression `formula` is the body of the function `f`.```
````f = symfun(formula,inputs)` is the formal way to create a symbolic function.```

## Examples

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Define the symbolic function `x + y`. First, create the function by using `syms`. Then define the function.

```syms f(x,y) f(x,y) = x + y```
```f(x, y) = x + y```

Find the value of `f` at `x = 1` and `y = 2`.

`f(1,2)`
```ans = 3```

Define the function again by using the formal way.

```syms x y f = symfun(x+y,[x y])```
```f(x, y) = x + y```

Return the body of a symbolic function by using `formula`. You can use the body for operations such as indexing into the function. Return the arguments of a symbolic function by using `argnames`.

Index into the symbolic function `[x^2, y^4]`. Since a symbolic function is a scalar, you cannot directly index into the function. Instead, index into the body of the function.

```syms f(x,y) f(x,y) = [x^2, y^4]; fbody = formula(f); fbody(1) fbody(2)```
```ans = x^2 ans = y^4```

Return the arguments of the function.

`fvars = argnames(f)`
```fvars = [ x, y]```

## Input Arguments

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Function body, specified as a symbolic expression, vector of symbolic expressions, or matrix of symbolic expressions.

Example: `x + y`

Input argument or arguments of a function, specified as a symbolic variable or an array of symbolic variables, respectively.

Example: `[x,y]`

## Output Arguments

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Function, returned as a symbolic function (`symfun` data type).