[erlang-questions] How to write this code better?
Mon Apr 14 11:11:36 CEST 2008
> 0. Never write a literal value for pi.
> 3.14159 is *wrong*. Use math:pi() instead.
Even math:pi() is *absolutely wrong* too and every numerical value you
give to Pi is wrong. I have learnt this when I were, decades ago, a
student in physics (yes, I have had a degres in physics before becoming
However, the correctness of a number depends on the context where you
are using it.
> So where does 89.99 come from? Why is it 89.99 rather than 89.999?
> Just how accurate *is* this formula anyway?
In many real world applications 89.9, 89.99 and 9.999 give the same
See this image:
It is the snapshop of a program I wrote many years ago using a very
sophisticated sun position algorithm taking in consideration many
factors. I normaly use it in my job to find the better orientation of a
building and the positions and the dimensions of windows. The results
are very accurated. However using the small and very simple program
and after to Erlang) gives results that are very similar to those given
by the sophisticated one and could be applied for real world
applications :-) For doing practical applications like daylight,
sunlight, reinforced concrete calculations and many many others, I find
writing small and simple applications (as set of functions) in Erlang
using its interpreter as a calculator helps me very much during design
and preliminary calculations (architecture and civil engineering speaking).
In many architecture applications an error even equal to 10% is to be
considered technically correct :-).
*I am an architect which means a practical man and I find Erlang really
helpful to be used this way*.
However, thank you for you advices!
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