# Documentation

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# evalin

Evaluate MuPAD expressions without specifying their arguments

## Syntax

```result = evalin(symengine,MuPAD_expression)[result,status] = evalin(symengine,MuPAD_expression)```

## Description

`result = evalin(symengine,MuPAD_expression)` evaluates the MuPAD® expression `MuPAD_expression`, and returns `result` as a symbolic object. If `MuPAD_expression` throws an error in MuPAD, then this syntax throws an error in MATLAB®.

```[result,status] = evalin(symengine,MuPAD_expression)``` lets you catch errors thrown by MuPAD. This syntax returns the error status in `status` and the error message in `result` if `status` is nonzero. If `status` is 0, `result` is a symbolic object; otherwise, it is a character vector.

## Input Arguments

 `MuPAD_expression` Character vector containing a MuPAD expression.

## Output Arguments

 `result` Symbolic object or character vector containing a MuPAD error message. `status` Integer indicating the error status. If `MuPAD_expression` executes without errors, the error status is 0.

## Examples

Compute the discriminant of the following polynomial:

`evalin(symengine,'polylib::discrim(a*x^2+b*x+c,x)')`
```ans = b^2 - 4*a*c```

Try using `polylib::discrim` to compute the discriminant of the following nonpolynomial expression:

`[result, status] = evalin(symengine,'polylib::discrim(a*x^2+b*x+c*ln(x),x)')`
```result = 1×39 char array An arithmetical expression is expected. status = 2```

## Alternatives

`feval` lets you evaluate MuPAD expressions with arguments. When using `feval`, you must explicitly specify the arguments of the MuPAD expression.

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### Tips

• Results returned by `evalin` can differ from the results that you get using a MuPAD notebook directly. The reason is that `evalin` sets a lower level of evaluation to achieve better performance.

• `evalin` does not open a MuPAD notebook, and therefore, you cannot use this function to access MuPAD graphics capabilities.