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.,





 






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