[Gnuplot-info] Why for can't print? (and suggestions about help print)

[Marc C. <mc...@un...>]

hello people,

I'm considering using gnuplot to replace bc in some cases.

There the for loop can be used for ploting and setting things.
as the help says

       plot for [filename in "A.dat B.dat C.dat"] filename using 1:2 with lines
       plot for [basename in "A B C"] basename.".dat" using 1:2 with lines
       set for [i = 1:10] style line i lc rgb "blue"
       unset for [tag = 100:200] label tag

however, it can't be used with print and the do loop requires {} even
for 1 instruction. so when (what i think as) the "natural way" for
a gnuplot beginner is

    f(x) = 2 * x + 3
    print for [ x = 0:20:2 ] x, f(x)

i have to write

    f(x) = 2 * x + 3
    do for [ x = 0:20:2 ] {print x, f(x) }

is there an internal/conceptual reason for print to not work like the
others instructions?

also: i would like to suggest adding some examples in the gnuplot help
print section:

 Syntax:
       print <expression> {, <expression>, ...}

to demonstrate that's it's easy to cast a num as string by using "".
my update should be

 Syntax:
       print <expression> {, <expression>, ...}

 Examples:

       # print some text data
       print "hello world"
       # print some numeric data
       x=12
       print 12,x
       # print combined data (first element *must* be a string)
       print "".x." was the result"

also: i would like to know if there is a way to choose the expression
separator. so i can write

    print x, f(x), g(x)

instead of

    print "".x. ",".f(x). ",".g(x)

thanks for helping.
regards,

-- 
Marc Chantreux
Direction du numérique de l'Université de Strasbourg
Pôle de Calcul et Services Avancés à la Recherche (CESAR)
http://annuaire.unistra.fr/p/20200