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For 2023 (and 2024 ...) - we are now fully retired from IT training.
We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.

Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!

I am also active in many other area and still look after a lot of web sites - you can find an index ((here))
Problems with small numbers

Posted by triclosan (triclosan), 27 July 2005
I have a problem if value of variable about 1e-09 or smallest. I can't do any mathematic operation with it. How I can increase number of units after decimal point?

Posted by admin (Graham Ellis), 28 July 2005
Tcl is an unusual language in that everything is held as / converted to string internally, so it's inefficient and probably the wrong language choice for programs that are heavily calculation based / doing very clever things with numbers.  Heck - look at the whole "expr" mechanism - neat and short and easy it isn't.

Programs that are getting involved with very large / very small numbers tend to do quite a bit of calculation, so I'm wondering if your application would be better suited to another language? You'll not it's very rare I suggest this, but I'm doing so here on the basis of your question.

Still want to stick with Tcl?   Options open to you include:
a) Scaling all your calculaations - multiply by 1000 prior to the numbers getting so tiny.  i.e. work in Metres rather than Kilometres.
b) Doing your calculations within embedded C code.



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