|$Math::Sequence::Parser||This scalar contains a Parse::RecDescent parser to parse formulas. It is derived from the Math::Symbolic::Parser grammar.|
|$Math::Sequence::warnings||This scalar indicates whether Math::Sequence should warn about the performance implications of using the back() method on uncached sequences. It defaults to true.|
new() The constructor for Math::Sequence objects. Takes two or three arguments. In the two argument form, the first argument specifies the recursion definition. It must be either a string to be parsed by a Math::Symbolic parser or a Math::Symbolic tree. In the two argument version, the recursion variable (the one which will be recursively replaced by its predecessor) will be inferred from the function signature. Thus, the formula must contain exactly one variable. The second argument must be a starting value. It may either be a constant or a Math::Symbolic tree or a string to be parsed as such. next() The next() method returns the next element of the sequence and advances the iterator by one. This is the prefered method of walking down a sequences recursion. cached() Returns a true value if the sequence is currently being cached, false if it isnt. By default, new objects have caching enabled. It is suggested that you only disable caching if space is an issue and you will only walk the sequence uni-directionally and only once.
cached() can be used to change the caching behaviour. If the first argument is true, caching will be enabled. If it is false, caching will be disabled.
current_index() Returns the index of the current element. That is, the index of the element that will be returned by the next call to the next() method.
This method also allows (re-)setting the element that will be next returned by the next() method. In that case, the first argument shoudl be the appropriate index.
Returns undef and doesnt set the current index if the argument is below 0.
at_index() This method returns the sequence element with the index denoted by the first argument to the method. It does not change the state of the iterator. This method is extremely slow for uncached sequences.
Returns undef for indices below 0.
back() This methods returns the sequence element previously returned by the next() method. Since it is extremely slow on uncached sequences, it warns about this performance hit by default. To turn this warning off, set the $Math::Sequence::warnings scalar to a false value.
This method decrements the current iterator sequence element.
Returns undef if the current index goes below 0.
Steffen Mueller, <sequence-module at steffen-mueller dot net<gt>
Math::Symbolic and Math::Symbolic::Parser for the kinds of formulas accepted by Math::Sequence.
|perl v5.20.3||MATH::SEQUENCE (3)||2004-02-14|