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 Robotics / RCX / legOS / 2333
2332  |  2334
Subject: 
Re: exponents, e^
Newsgroups: 
lugnet.robotics.rcx.legos
Date: 
Wed, 6 Mar 2002 14:02:24 GMT
Viewed: 
2016 times
  
you know i was looking at lejos, java for RCX, and it seems to have
exponents, trig, etc. functions built in. any advantages legOS has over
lejos i don't know about. if not, i think i may give it a whirl....
-dave


In lugnet.robotics.rcx.legos, Tom Oldfield writes:
Dave

I am working on a number of maths functions that includes
loge log10  expe and exp10 x^y as well as trig functions.  As
you note it requires the specification of the mantassa and exponent
desciption of the float variable for the RCX.  Usually this is
done in most maths libraries by splitting a variable using a union
desciption (float -> union  { float y; unsigned short bit[2]; }) - this
needs the endian encoding for the RCX.
I am conducting some tests but I get little more than a couple of
minutes/week to work on this.  In particular many maths functions
require the function x*2^n, and most current maths libraries are
at very least double/quad precision so conversion needs some thought.

Regards

tom


In lugnet.robotics.rcx.legos, David Dubravetz writes:
hello,
i've searched through the discussions but i haven't been able to find any
info on using floats with exponents in legOS, specifically the inverse of
natural log: e^. actually, i can't find any info about integers with
exponents either.  i am programming a backprop neural net to run on the RCX
that uses a sigmoid activation function: (1/(1 + e^(-D*net))). i've seen a
few posts on trig functions, but i really would prefer exponents if possible.
any suggestions/help would be appreciated.
thanks,
dave



Message has 1 Reply:
  Re: exponents, e^
 
(...) Only one I can think of off-hand is support for the remote control, I've been thinking about looking at that if I can get some time (though it's still only a patch in legOS, have to do something about that, too). There may be others I don't (...) (23 years ago, 6-Mar-02, to lugnet.robotics.rcx.legos)

Message is in Reply To:
  Re: exponents, e^
 
Dave I am working on a number of maths functions that includes loge log10 expe and exp10 x^y as well as trig functions. As you note it requires the specification of the mantassa and exponent desciption of the float variable for the RCX. Usually this (...) (23 years ago, 6-Mar-02, to lugnet.robotics.rcx.legos)

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