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Calculator Community => TI Calculators => Axe => Topic started by: Deep Toaster on October 10, 2011, 12:29:02 am

Title: 8.8 fixed point/inflation by 256 tutorial
Post by: Deep Toaster on October 10, 2011, 12:29:02 am

[This space is reserved for a BBCode version of this section of the tutorial when I finish it up.]

Here's my tutorial in response to http://omniurl.tk/10129/196558/ (http://omniurl.tk/10129/196558/). My working version is up at http://clrhome.org/tutorials/axe/07/ (and as you can probably tell, it'll be part of my general Axe tutorial (http://omniurl.tk/10614/)).

Suggestions? I'm afraid it might be a bit confusing the way it jumps between inflation by 256 and 8.8 fixed point, even though they're really the same thing. Any thoughts?

Title: Re: 8.8 fixed point/inflation by 256 tutorial
Post by: Quigibo on October 10, 2011, 01:34:13 am

You might want to note that there actually is a difference between 8.8 fixed point and inflation:  8.8 is signed while inflation is unsigned.  The fixed point multiplication and inverse routines won't work as expected for larger values if you're treating them as unsigned.  Another effect of that is that 8.8 numbers should be deflated with //256 instead of /256.

Your tutorial is about inflated numbers though, and it does a good job in that respect, you just don't want to make people think that those 2 methods are identical because the operations you do with them are slightly different.

Title: Re: 8.8 fixed point/inflation by 256 tutorial
Post by: Stefan Bauwens on October 10, 2011, 11:18:11 am

Thanks DeepThough. I quite understand this now. I just have to think of how to implant it in my code.