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#### NAME

```       Math::Calculus::Differentiate - Algebraic Differentiation Engine
```

#### SYNOPSIS

```         use Math::Calculus::Differentiate;

# Create an object.
my \$exp = Math::Calculus::Differentiate->new;

# Set a variable and expression.
\$exp->setExpression('x^2 + 5*x') or die \$exp->getError;

# Differentiate and simplify.
\$exp->differentiate or die \$exp->getError;;
\$exp->simplify or die \$exp->getError;;

# Print the result.
print \$exp->getExpression; # Prints 2*x + 5
```

#### DESCRIPTION

```       This module can take an algebraic expression, parse it into a tree
structure, modify the tree to give a representation of the
differentiated function, simplify the tree and turn the tree back into
an output of the same form as the input.

It supports differentiation of expressions including the +, -, *, / and
^ (raise to power) operators, bracketed expressions to enable correct
precedence and the functions ln, exp, sin, cos, tan, sec, cosec, cot,
sinh, cosh, tanh, sech, cosech, coth, asin, acos, atan, asinh, acosh
and atanh.
```

#### EXPORT

```       None by default.
```

#### METHODS

```       new
\$exp = Math::Calculus::Differentiate->new;

Creates a new instance of the differentiation engine, which can
hold an individual expression.

Sets a certain named value in the expression as being a variable. A
named value must be an alphabetic chracter.

setExpression
\$exp->setExpression('x^2 + 5*x);

Takes an expression in human-readable form and stores it internally
as a tree structure, checking it is a valid expression that the
module can understand in the process. Note that the engine is
strict about syntax. For example, note above that you must write
5*x and not just 5x. Whitespace is allowed in the expression, but
does not have any effect on precedence.  If you require control of
precedence, use brackets; bracketed expressions will always be
evaluated first, as you would normally expect. The module follows
the BODMAS precedence convention. Returns undef on failure and a
true value on success.

getExpression
\$expr = \$exp->getExpression;

Returns a textaul, human readable representation of the expression
that is being stored.

differentiate
\$exp->differentiate('x');

Differentiates the expression that was stored with setExpression
with respect to the variable passed as a parameter. Returns undef
on failure and a true value on success.

simplify
\$exp->simplify;

Attempts to simplify the expression that is stored internally. It
is a very good idea to call this after calling differentiate, as
the tree will often not be in the most compact possible form, and
this will affect the readability of output from getExpression and
the performance of future calls to differentiate if you are
intending to obtain higher derivatives. Returns undef on failure
and a true value on success.

getTraceback
\$exp->getTraceback;

When setExpression and differentiate are called, a traceback is
generated to describe what these functions did. If an error occurs,
this traceback can be extremely useful in helping track down the
source of the error.

getError
\$exp->getError;

When any method other than getTraceback is called, the error
message stored is cleared, and then any errors that occur during
the execution of the method are stored. If failure occurs, call
this method to get a textual representation of the error.
```

```       The author of this module has a website at
<http://www.jwcs.net/~jonathan/>, which has the latest news about the
module and a web-based frontend to allow you to test the module out for
yourself.
```

#### AUTHOR

```       Jonathan Worthington, <jonathan@jwcs.net>
```

```       Copyright (C) 2004 by Jonathan Worthington

This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself, either Perl version 5.8.1 or, at
your option, any later version of Perl 5 you may have available.
```

#### POD ERRORS

```       Hey! The above document had some coding errors, which are explained
below:

Around line 55:
'=item' outside of any '=over'

Around line 150:
You forgot a '=back' before '=head1'```

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