How can we find function value f1, f2,.......f15? If function is defined by fi = Xi +3*Xi+1 - 4Xi+2 + Xi+3 and Xi=[2 5 -6 8 9 45 4 4 4 4 8 9 4 1 5]; i=1,2,......15.

How can we find function value f1, f2,.......f15? If function is defined by fi = Xi +3*Xi+1 - 4Xi+2 + Xi+3 and Xi=[2 5 -6 8 9 45 4 4 4 4 8 9 4 1 5]; i=1,2,......15.

[Torsten]

You can only get f1,...,f12 (or you have values for X(-2), X(-1) and X(0)).

Best wishes

Torsten.

[Shivangi Chauhan]

Yes i have values?

[Torsten]

for k = 1:12
  f(k) = X(k)+3*X(k+1)-4*X(k+2)+X(k+3);
end

Best wishes

Torsten.

[Shivangi Chauhan]

how to define Xi?

[Torsten]

X=[2 5 -6 8 9 45 4 4 4 4 8 9 4 1 5]; 
for k = 1:12
  f(k) = X(k)+3*X(k+1)-4*X(k+2)+X(k+3);
end

[Shivangi Chauhan]

Thanks,a lot

Answer 1

[Andrei Bobrov]

f = conv(Xi,[1 -4 3 1],'valid');

[Shivangi Chauhan]

Sir, plz explain in detail. not able to implement.

[Andrei Bobrov]

please see here