Ti-BD Teasers #2: Logarithm

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Summary:

The first one went quickly. Here's another

Ti-BD Teasers #2: Logarithm

Michael (guest) 27 Sep 2015 20:03

Okay, the first one went quickly.

The challenge:
Create a logarithm program.

The rules:
The base must be in B and the number in A. The answer must be returned in Ans and X.
You may not use logarithms, exponents, roots, or the solve( function.
Exponents include e^( and 10^(.

The target size:
25 bytes or smaller.

Re: Ti-BD Teasers #2: Logarithm

lirtosiast 27 Sep 2015 21:58

Are we allowed to use ⁻¹, ², or ³?

Re: Ti-BD Teasers #2: Logarithm

lirtosiast 27 Sep 2015 22:02

There ain't no rule against cosh⁻¹(.

21 bytes:

cosh⁻¹(.5A+.5/A)/cosh⁻¹(.5B+.5/B→X

I can save a byte if ⁻¹ is allowed:

cosh⁻¹(.5A+.5/A)/cosh⁻¹(.5(B+B⁻¹→X

Last edited on 27 Sep 2015 22:02 by lirtosiast Show more

Michael (guest) 27 Sep 2015 23:28

Wow. I too used hyperbolic functions:

tanh-1((A-1)/(A+1))/tanh-1((B-1)/(B+1 -> X         \\That's the inverse hyperbolic tangent

Since you're so good, lirtosiast, you give the next one!

Josiah W 29 Sep 2015 07:50

lirtosiast is excellent at TI-BASIC programming. Give him a task, he'll pump out a fully optimized implementation in TI-BASIC given a minute or two :P .
I still remember how he helped me with game-over checking for my BASIC Bejeweled game that took only 2-3 seconds to execute. (thanks for that, BTW)

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