Given an expression involving known constants, integration in finite terms, computation of limits, etc., the constant problem is the determination of if the expression is
equal to zero. The constant problem, sometimes also called
the identity problem (Richardson 1968) is a very difficult unsolved problem in transcendental
number theory. However, it is known that the problem
is undecidable if the expression involves oscillatory
functions such as sine. However, the Ferguson-Forcade
algorithm is a practical algorithm for determining if there exist integers for given real numbers such that

or else establishing bounds within which no relation can exist (Bailey 1988).

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1999. http://arxiv.org/abs/cs.DS/9907011.Richardson,
D. "Some Unsolvable Problems Involving Elementary Functions of a Real Variable."
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Computation, Berkeley, July 27-29, 1992 (Ed. P. S. Wang). ACM Press,
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