Recursive Function with two Base Cases

2013 2 19
1 个回答
1 次查看（30 天）

0 个投票

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!

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回答（1 个）

Azzi Abdelmalek
Azzi Abdelmalek 2013-2-19
编辑：Azzi Abdelmalek 2013-2-19

0 个投票

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)

5 个评论
显示 3更早的评论 隐藏 3更早的评论

MiauMiau
MiauMiau 2013-2-19
Unfortunately, that answer doesn't help
MiauMiau
MiauMiau 2013-2-19
编辑：Azzi Abdelmalek 2013-2-19
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
Azzi Abdelmalek 2013-2-19
编辑：Azzi Abdelmalek 2013-2-19
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
MiauMiau 2013-2-19
now it works, thanks!

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MiauMiau
MiauMiau
2013-2-19

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