Cal"cu*lus (?), *n.*; *pl.*
**Calculi** (#). [L, *calculus*. See
__Calculate__, and __Calcule__.] **1.**
*(Med.)* Any solid concretion, formed in any part of
the body, but most frequent in the organs that act as reservoirs,
and in the passages connected with them; as, biliary
*calculi*; urinary *calculi*, etc.

**2.** *(Math.)* A method of
computation; any process of reasoning by the use of symbols; any
branch of mathematics that may involve calculation.

**Barycentric calculus**, a method of
treating geometry by defining a point as the center of gravity of
certain other points to which coĆ«fficients or weights are
ascribed. -- **Calculus of functions**,
that branch of mathematics which treats of the forms of
functions that shall satisfy given conditions. --
**Calculus of operations**, that branch of
mathematical logic that treats of all operations that satisfy
given conditions. -- **Calculus of
probabilities**, the science that treats of the
computation of the probabilities of events, or the application of
numbers to chance. -- **Calculus of
variations**, a branch of mathematics in which the
laws of dependence which bind the variable quantities together
are themselves subject to change. -- **Differential
calculus**, a method of investigating mathematical
questions by using the ratio of certain indefinitely small
quantities called *differentials*. The problems are
primarily of this form: to find how the change in some variable
quantity alters at each instant the value of a quantity dependent
upon it. -- **Exponential calculus**, that
part of algebra which treats of exponents. --
**Imaginary calculus**, a method of
investigating the relations of real or imaginary quantities by
the use of the imaginary symbols and quantities of algebra.
-- **Integral calculus**, a method which in the
reverse of the differential, the primary object of which is to
learn from the known ratio of the indefinitely small changes of
two or more magnitudes, the relation of the magnitudes
themselves, or, in other words, from having the differential of
an algebraic expression to find the expression itself.