Recursive Function with two Base Cases

Hi

Let the Lucas Numbers be defined as follows:

1 for n = 1
3 for n = 2
L_n = L_(n-1) + L_(n-2) for n >= 3

Why doesn't my code work? Here is the code:

function a = lucas(N)
N = input('please enter an integer:')
if N == 1
    a = 1;
elseif N == 2
    a = 3;
elseif 
    a = lucas(N-1)+ lucas(N-2)
end
 disp(N)
end

thanks!

Answer 1

[Azzi Abdelmalek]

It's not elseif use else

Also you are using a function with input argument N, why in your function you added:

N = input('please enter an integer:')

What you should do is:

function a = lucas(N)
if N == 1
  a = 1;
elseif N == 2
  a = 3;
else 
  a = lucas(N-1)+ lucas(N-2)
end
disp(N)

And in windows command

N = input('please enter an integer:')
a=lucas(N)

[MiauMiau]

Unfortunately, that answer doesn't help

[Azzi Abdelmalek]

You should try it.

[MiauMiau]

although you have edited your answer now,

1. the programms output is not according to the rules defined above. N = 4 for instance should give an output of 7.
2. the program stays in an infinte loop.

[Azzi Abdelmalek]

I forget to remove , input from your function. It gives 7 for N=4

save this function

function a = lucas(N)
if N == 1
a = 1;
elseif N == 2
a = 3;
else 
a = lucas(N-1)+ lucas(N-2)
end
disp(N)

in windows command type

lucas(4)

[MiauMiau]

now it works, thanks!