mixed integer

Hello,

Could someone please explain me meaning of mixed integer? As far as I know integer has only one meaning and that is whole number. So does it mean that mixed integer is some kind of number?

Context is as follows:

You need someone who has a handle on the laws of hydrodynamic resistance. The heat exchange
in oil-mixture flows. You also need someone who can work with mixed integer programs. You're gonna have to resize the pipes
as you work across uneven terrain.

It comes from first episode of Fringe serial.

Thanks a lot for answer.

The phrase you want is mixed integer programs

Rather than explain in depth: - http://en.wikipedia.org/wiki/Integer_programming#Mixed_Integer_and_Zero-one_Linear_Programs

Mixed integer linear programming (MILP) involve problems in which only some of the variables, xi, are constrained to be integers

The problem in understanding the original phrase is that "integer" is not a noun. It is part of an adjectival phrase, mixed integer. The phrase modifies the noun program. As PaulQ posted, a mixed-integer program is a type of linear programming model. (It's easier to see the grammatical structure if we put a hyphen in mixed-integer, but people who work with such models generally don't use one.)