Scheme: simple recursion

Question

My recursive function multiplies the given area by 1.5 until it reaches 100,000. The output is supposed to be how many times it had to multiply by 1.5. I think I understand most of what I need to do, but I'm not sure what to put in my (if) statement.

(define area-multiplier (lambda (area) (if (< 100000 area) 0 ;what do I put here? (+ 1 (area-multiplier (* area 1.5))))))

John Clements · Accepted Answer · 2012-09-18 16:45:13Z

1

Think about this using an example. In this case, the relevant examples are

(area-multiplier 100000)

and

(area-multiplier 100001)

What should these produce?

answered Sep 18, 2012 at 16:45

John Clements

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jblittle Over a year ago

Oh, I understand. I want them to produce the amount of times area was multiplied by 1.5. Therefore, 0 was correct in that spot because it would add 0 to the total and stop recursion. Thanks!

C. K. Young · Accepted Answer · 2012-09-18 16:26:56Z

0

What you have is fine, except that if you want 100000 to return 0, then change the < to <=. :-)

answered Sep 18, 2012 at 16:26

C. K. Young

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1 Comment

jblittle Over a year ago

I didn't even catch that. Thank you! It turned out I had a fundamental misunderstanding of how recursion worked!

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