25.08.2021 Views

082-Engineering-Mathematics-Anthony-Croft-Robert-Davison-Martin-Hargreaves-James-Flint-Edisi-5-2017

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

22.6 Numerical solution of difference equations 695

EXERCISES22.5

1 Atransduceris used to measure the speed ofamotor

car.Design adigital filterto calculate the distance

travelled bythe car.

2 Draw a block diagram forEquations(22.5)

and (22.6).

Solutions

1 s[n] =s[n −1] +Tv[n]. SeeFigure S.25.

y[n]

3 S

s[n]

T

T

FigureS.25

22.6 NUMERICALSOLUTIONOFDIFFERENCEEQUATIONS

Having seen how difference equations are formulated we now proceed to methods of

solution. The numerical method illustrated may be applied to all classes of difference

equation.

Example22.6 Given

x[n+1]−x[n]=n

x[0]=1

determinex[1],x[2] andx[3].

Solution Thetermsinthe equation areevaluated forvarious values ofn:

n = 0

x[1] −x[0] = 0

x[1] = 1

n = 1

x[2] −x[1] = 1

x[2] = 2

n = 2

x[3] −x[2] = 2

x[3] = 4

Example22.7 Determinex[4]given

2x[k +2] −x[k +1] +x[k] = −k 2 x[0] = 1 x[1] = 3

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!