Will this algorithm always work?

Question

So I'm writing a TI-BASIC algorithm for my calculator that does ratios. Here is the code:

Disp "GIVE ONE NUMBER"
Prompt A
Disp "GIVE A SECOND NUMBER"
Prompt B
While fPart(A)≠0 or fPart(B)≠0
A*10->A
B*10->B
End
gcd(A,B)->C
Disp A/C
Disp B/C

It seems to work in most cases. Are there any flaws/corner cases of this code that I have not noticed? Thanks.

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score 2 · Accepted Answer · answered Jun 13 '13 at 22:32

2

It will work, but there is an even cooler way to do it with no loops.

Disp "GIVE ONE NUMBER"
Prompt A
Disp "GIVE A SECOND NUMBER"
Prompt B
1/fPart(A)->F
A*F->A
B*F->B
1/fPart(B)->F
A*F->A
B*F->B
gcd(A,B)->C
Disp A/C
Disp B/C

answered Jun 13 '13 at 22:32

Jean-Bernard Pellerin

12,556
10
57
79

So you definitely think that both will work? Also I'm guessing the advantage of your algorithm is it's faster? – Someone Jun 13 '13 at 22:40
I don't know if it's faster. Mine has the potential for rounding issues with division. Both solutions should work though. – Jean-Bernard Pellerin Jun 13 '13 at 22:41
Wait a sec. This won't work if the original numbers are integers – Someone Jun 13 '13 at 22:48
@someone haha oops, I guess there needs to be a check before the division so that it's not dividing by 0. – Jean-Bernard Pellerin Jun 13 '13 at 22:49
I guess I'll just have to add the integer checking myself – Someone Jun 13 '13 at 22:49
Just check at the beginning and if yes skip the 1/fpart stuff and go right to gcd, correct? – Someone Jun 13 '13 at 22:50
@Someone You'd have to check before each 1/fpart, it's possible that the first fpart will make both values integers. ex: 1.5,2.5 -> 3,5 -> division by 0. – Jean-Bernard Pellerin Jun 13 '13 at 22:51
1

Ah very true. You know, maybe for the time being I will use my own algorithm :) – Someone Jun 13 '13 at 22:52

score 1 · Answer 2 · answered Jul 03 '15 at 19:26

1

Yes it will work and so will Jean-Bernard Pellerin's answer, but to best clean it up:

Input "GIVE ONE NUMBER",A
Input "GIVE A SECOND NUMBER",B
1/fPart(A)->F
A*F->A
B*F->B
1/fPart(B)->F
A*F->A
B*F->B
gcd(A,B)->C
Disp A/C
Disp B/C

answered Jul 03 '15 at 19:26

Moshe Goldberg

461
2
15

Will this algorithm always work?

2 Answers2