Showing posts with label Linear Programming problem. Show all posts
Showing posts with label Linear Programming problem. Show all posts

Thursday, 28 November 2013

Linear Programing Problem(LPP)


Linear Programming Problem(LPP)

An equation with same degree/variable/power is a Ist order equation.
LP model has few basic elements which are described below.

Decision Variable  - The variable whose values determine the solution of a problem.
Objective function - the generalized format of an objective function is given as
maximize or minimize z =c1x1+c2x2 +.........+cnxn
where c1,c2,...cn are cost variables and x1,x2 ...xn are decision variables.

Technical Coefficient : (aij)
aij is the amount of resource i required for the activity j where i varies from 1 to m and j varies from 1 to n.
The generalized format of technical coefficient is 
[ a11 a12 .....a1n
  a21 a22 .....a2n 
  .
  .
  am1 am2 ... amn ]

Resource Availability: (bi)
The constant bi is the amount of resource i available during the planning period.
The general format is given as,
[b1
 b2
 .
 .
 bm]

Set of Constraints:
A constraint is a kind of restriction on the total amount of a particular resource required to carry out activities atvarious levels.
The generalized format is given as:
a11x1+a12x2+...+a1nxn <=,= or  >= b1
a21x1+a22x2+...+a2nxn <=, = or >= b2
.
.
am1x1+am2x2+...+amnxn<= ,= or >=bm

Non negativity constraint:
Each and every decision variable in LP model is a non negative variable.
The general format is
x1,x2..xn >=0

Mathematical formulation of LPP:
The general format is given by
Maximize/Minimize z = c1x1+c2x2+...+cnxn  --- (1 )
subjected to constraints
a11x1+a12x2+...+a1nxn <=,= or >= b1
a21x1+a22x2+...+a2nxn <=,= or >= b2
.                                                                        ---(2)
.
an1xn+anx2+...+amnxn<= , = or >=bm

and x1,x2,...xn >=0                                         ---(3)
variables are involved .

Definition of LPP :
Linear Programming problem deals with optimization of functions of decision variables known as objective functions subject to a set of simultaneous linear eqution known as constraints.
Applications:
LP technique is used in many indusrial and economic problems , airlines , railways, food processing etc.,