Can someone explain how this recursive function works step by step?

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AStar
AStar 2019-12-1
评论： AStar 2019-12-1
function outvar = recurfn(num) % Format: recurfn(number)
if num < 0
outvar = 2;
else
outvar = 4 + recurfn(num-1);
end
end
Can someone explain to me how this recursive function works step by step?
for example without using MATLAB how would i figure out the result of recurfn(1) or recurfn(2)?
Thanks!

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采纳的回答

Stephane
Stephane 2019-12-1
编辑：Stephane 2019-12-1
You simply add the sequence over and over (decreasing num by 1 each time), up until you reach the stop signal (num < 0).
This gives
recurfn(2) = 4 + recurfn(1)
= 4 + [ 4 + recurfn(0) ]
= 4 + 4 + [ 4 + recurfn(-1) ]
= 4 + 4 + 4 + 2

更多回答（1 个）

Jesus Sanchez
Jesus Sanchez 2019-12-1
function outvar = recurfn(num) % Format: recurfn(number)
if num < 0
outvar = 2;
else
outvar = 4 + recurfn(num-1);
end
end
As fas as I understand this, the function will call itself forever until num has a value less than 0. Thus, outvar is fixed to 2.
  2 个评论
AStar
AStar 2019-12-1
Thanks for your answer, but I dont think you understand my question. I am asking for an explanation of the logic required to answer this question without using the MATLAB software. How can one determine for example recurfn(2), recurfn(4) etc without actually calling those in the command window.

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