From: Mark Sparshatt <msparshatt@...>
Date: 2004-05-20T07:07:41+09:00
Subject: Re: Fortran Format?

Qubert wrote:

>OK, I have an algorithm that I created to format a series of numbers
>for a column centric FORTRAN routine to use.  I don't like what I have
>created, although it works, so I would like to ask if anyone here has
>a more cleaver way.
>
>Problem:  I have a series of numbers that need to be formated as a
>FORTRAN program would.  That is, FORTRAN cares more about columns than
>numbers so I need to fake the output of Ruby to make it look "decimal
>justified".
>
>Example, a series of numbers:
>3.15, 122.5, 303.123, 55.0
>Input for C or Ruby (the space means a new number):
>3.15 122.5
>303.123 55.0
>Input needed for FORTRAN with format (f7.3,f5.1):
>  3.150122.5 
>303.123 55.0
>
>My Ruby hack to put spaces at the begining if necessary:
>def ff(num,len1,len2)
>  x = num.to_s.split(".")
>  numstring = ""
>  x[0].size.upto(len1 - 1) {|b| numstring << ' '}
>  numstring << x[0] << "."
>  numstring << x[1][0..len2]
>end
>
>code...
>bla ...
>printf("%s %s\n", ff(3.150,3,3),ff(122.5,3,1)
>printf("%s %s\n", ff(303.123,3,3),ff(55.0,3,1)
>
>  
>
A better way would be to be to use the sprintf method (documented on 
page 427 of the pickaxe) to format the string.

The following code does what you want

def ff(num, len1, len2)
    sprintf("%#{len1 + len2 + 1}.#{len2}f", num)
end

printf("%s %s\n", ff(3.150,3,3),ff(122.5,3,1))
printf("%s %s\n", ff(303.123,3,3),ff(55.0,3,1))


>I know that this needs improvement so your help would be appreciated.
>I have to interface with these types of FORTRAN programs a lot, thus
>far I have avoided this.
>  
>
HTH

--

Mark Sparshatt