injection

Webster's Dictionary (GCIDE)

1.The act of injecting or throwing in; -- applied particularly to the forcible insertion of a liquid or gas, by means of a syringe, pump, etc. [1913 Webster]

2.That which is injected; especially, a liquid inserted thrown into a cavity of the body by a syringe or pipe; a clyster; an enema. --Mayne. [1913 Webster]

3.(Anat.) (a) The act or process of filling vessels, cavities, or tissues with a fluid or other substance. (b) A specimen prepared by injection. [1913 Webster]

4.(Steam Eng.) (a) The act of throwing cold water into a condenser to produce a vacuum. (b) The cold water thrown into a condenser. [1913 Webster]

Injection cock, or Injection valve (Steam Eng.), the cock or valve through which cold water is admitted into a condenser.

Injection condenser. See under Condenser.

Injection pipe, the pipe through which cold water is through into the condenser of a steam engine.

fuel injection, a method of inserting fuel into internal-combustion engines by directly forcing the liquid fuel into the combustion chamber at an appropriate point in the piston cycle; in contrast to carburetion, in which an air-fuel mixture is drawn in by the downward stroke of the piston. [1913 Webster +PJC]

Free On-line Dictionary of Computing

1.<mathematics> A function, f : A -> B, is injective or one-one, or is an injection, if and only if

for all a, b in A, f(a) = f(b) => a = b.

I.e. no two different inputs give the same output (contrast many-to-one). This is sometimes called an embedding. Only injective functions have left inverses f' where f'(f(x)) = x, since if f were not an injection, there would be elements of B for which the value of f' was not unique. If an injective function is also a surjection then is it a bijection.

2.<reduction> An injection function is one which takes objects of type T and returns objects of type C(T) where C is some type constructor. An example is

f x = (x, 0).

The opposite of an injection function is a projection function which extracts a component of a constructed object, e.g.

fst (x,y) = x.

We say that f injects its argument into the data type and fst projects it out.

(1995-03-14)