🚀 go-pugleaf

Here is a macro for fixed point addition.

USAGE \FPadd{num1}{num2}\cs

This sets \cs to num1+num2.

Rules:

  num1 and num2 should have the same number of digits to the
    right of the decimal. (Exception: if num1 is an integer,
    decimal not needed.)
  num1 and num2 should have at least one digit to the left
    of the decimal (e.g., 0)
  num1 and num2 can have at most 8 digits on each side of the
    decimal.
  Negative numbers are OK.

DOES ANYONE HAVE ANY BETTER IDEAS? IT SEEMS LIKE A LOT OF
WORK FOR SOMETHING SO SIMPLE!!

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\catcode`\@=11

\newcount\multido@cnta
\newcount\multido@cntb
\newcount\multido@cntc
\newcount\multido@cntd

\def\@empty{}

\def\FPadd#1#2#3{%
  \edef\multido@tempa{#1..\noexpand\@nil#2}%
  \expandafter\FPadd@\multido@tempa..\@nil
  \let#3\multido@tempa}
\def\FPadd@#1.#2.#3\@nil#4.#5.#6\@nil{%
  \multido@cnta=#1\relax
  \multido@cntc=#4\relax
  \multido@cntd=#5\relax
  \multido@cntb=\@ne
  \FPadd@@@#500000000\@nil
  \ifnum#11<0
    \multido@cntb=-\multido@cntb
    \multiply\multido@cntb by 2
    \multido@cnta=-\multido@cnta
  \fi
  \ifnum#41<0
    \multido@cntb=-\multido@cntb
    \multido@cntc=-\multido@cntc
  \fi
  \ifnum\multido@cntb>0
    \advance\multido@cnta\multido@cntc
    \advance\multido@cntd0#2
    \ifnum\multido@cntd<\multido@tempa\relax
      \advance\multido@cntd\multido@tempa\relax
    \else
      \advance\multido@cnta 1
    \fi
    \expandafter\FPadd@@\the\multido@cntd\@empty\@nil
      {\ifnum\multido@cntb>\@ne-\fi}%
  \else
    \ifnum\multido@cnta>\multido@cntc\else
      \ifnum\multido@cnta=\multido@cntc
        \ifnum\multido@cntd>0#2
          \multido@cntb=-\multido@cntb
        \fi
      \else
        \multido@cntb=-\multido@cntb
      \fi
    \fi
    \ifnum\multido@cntb<\z@
      \advance\multido@cnta-\multido@cntc
      \multido@cntc=0#2\relax
      \advance\multido@cntc-\multido@cntd
    \else
      \advance\multido@cntc-\multido@cnta
      \multido@cnta=\multido@cntc
      \advance\multido@cntd-0#2
      \multido@cntc=\multido@cntd
      \advance\multido@cntb-1
    \fi
    \ifnum\multido@cntc<\z@
      \advance\multido@cntc\multido@tempa\relax
      \advance\multido@cnta-1
    \fi
    \advance\multido@cntc\multido@tempa\relax
    \expandafter\FPadd@@\the\multido@cntc\@empty\@nil
      {\ifnum\multido@cntb=-2-\fi}%
  \fi}
\def\FPadd@@#1#2#3\@nil#4{%
  \edef\multido@tempa{%
    #4\the\multido@cnta\ifx#2\@empty\else.#2#3\fi}}
\def\FPadd@@@#1#2#3#4#5#6#7#8#9\@nil{\def\multido@tempa{1#9}}
    
    
\FPadd{-13.42}{3.33}\tempa

\message{***\tempa***}

\bye
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Tim
-- 
Timothy Van Zandt   (609)258-4050  tvz@Princeton.EDU (NeXTMail)
Dept. of Economics,  Princeton University,  Princeton, NJ 08544