Post by thread:[PIC]: Hi-Tech C maths problem?

Hi Folks!, I am trying to use picclite to do a little maths on my pic i/o I am using #include <math.h> then in main float a, b=2, c=2; // simple test a=pow(b,c); // This compiles no trouble but when it links it produces lots of errors similar to this:- ::Cant find 0x5B words(0x5B withtotal) for psect text0 in segment CODE I am using a 16F84 and the default linker settings. Anybody got any ideas what could be wrong?. Is anyone successfully using maths functions on the 16F84? Ta John -- http://www.piclist.com hint: To leave the PICList spam_OUTpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu

Thanks for that Andy, yes I tried compiling with some different maths functions, the log(x) function uses 599 words and the sqrt(x) function uses 573 words, I will have to think of something else, If I use any maths functions using the 16F84 I won't have much room left for my program!. On Fri, 17 Nov 2000, Andy Jancura wrote: {Quote hidden}> >Hi Folks!, I am trying to use picclite to do a little maths on my pic i/o > >I am using #include <math.h> > > > >then in main float a, b=2, c=2; // simple test > > a=pow(b,c); // > > > >This compiles no trouble but when it links it produces lots of errors > >similar to this:- > > > >::Cant find 0x5B words(0x5B withtotal) for psect text0 in segment CODE > > > >I am using a 16F84 and the default linker settings. > > > >Anybody got any ideas what could be wrong?. > >Is anyone successfully using maths functions on the 16F84? > > Library code for pow() has little bit more than 1024 words. > > Andrej > _________________________________________________________________________ ----- John P. Brown .....J.P.BrownKILLspam@spam@bradford.ac.uk ---- \ --- Witty remark goes here --- / -------------------------------------------------- -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestKILLspammitvma.mit.edu

On Fri, 17 Nov 2000, JP.BROWN wrote: > Thanks for that Andy, yes I tried compiling with some different maths > functions, the log(x) function uses 599 words and the sqrt(x) function > uses 573 words, I will have to think of something else, If I use any maths > functions using the 16F84 I won't have much room left for my program!. Well, you could use integer arithmetic instead of floating. What's the application? -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestKILLspam.....mitvma.mit.edu

Hi Scott, the application will be producing a linear o/p from a variety of sensors such LDRs etc. I am considering using a lookup table to do the job. ----- John On Fri, 17 Nov 2000, Scott Dattalo wrote: > On Fri, 17 Nov 2000, JP.BROWN wrote: > > > Thanks for that Andy, yes I tried compiling with some different maths > > functions, the log(x) function uses 599 words and the sqrt(x) function > > uses 573 words, I will have to think of something else, If I use any maths > > functions using the 16F84 I won't have much room left for my program!. > > Well, you could use integer arithmetic instead of floating. What's the > application? -- http://www.piclist.com hint: To leave the PICList EraseMEpiclist-unsubscribe-requestspam_OUTTakeThisOuTmitvma.mit.edu

J.P. Brown wrote: > Thanks for that Andy, yes I tried compiling with some different maths > functions, the log(x) function uses 599 words and the sqrt(x) function > uses 573 words, I will have to think of something else, If I use any maths > functions using the 16F84 I won't have much room left for my program!. This is way too much even for floating point! I know for sure sqrt(x) takes 87 instructions for 24 bit float using PIC16 instruction set. You can easily include that in assembly as a C function, only conversion between Microchip and IEEE floating point representation would be required (it's just three instructions either way). The routine (and conversion) is at http://www.piclist.com BTW, it was debugged recently. And log(x) might take around 200 instructions if implemented using the CORDIC method. If you can tolerate ~0.05% error it can be even smaller and faster with a 16 entries table. For example, take a look at "[PIC]: [MATH] x^y routine implementation" thread in September. Good luck, Nikolai -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads