PtokaX forum

-- declare variables
local radicand

-- struct
    for x=-5 , 5 do
        radicand=x^2-9
       
        print( x , radicand )  -- TEST: display variables

        if radicand>=0 then
            print( x , sqrt(radicand) )
        else
            print( x , "unreal number" )
        end
 
    end



produces:

Quote-5   16
lua: drc_testIfStruct.lua:11: attempt to call global `sqrt' (a nil value)
stack traceback:
   drc_testIfStruct.lua:11: in main chunk
   [C]: ?

why?

TIA
doco

Ise'nt it math.sqrt and not "sqrt"..

Error is clear: a nil value; means that sqrt don't exist.
In some cases you need to load the math lib yourself before you can use it.

/Bluebear

QuoteIse'nt it math.sqrt and not "sqrt"..

You're most likely correct.  I am just learning and have found that none of the other 'global' functions or constants are working either.  Evidently because they're are not finding those 'class libraries'.

I tried your suggestion and works fine.  Which leads me to another qestion: is there an 'API' or list of these class libraries somewhere?  and what those libraries contain?

Thanks
doco