# New command Long division help

I posted before this thread.

I'm trying to automate this process - long division by Bulgarian(and many other countries) method. The desired one is the left, the right is from longdiv package. Here is the comparison.

I have tried xlop, longdiv(on the pic) but there is not package for the left equation which I need. I tried to edit longdiv.tex but i got some errors and I dont have good understanding of Latex. I hope someone will make function for that(I don't need fractions). Many people may need it. The from the pic is there.

## 1 Answer

The following does produce the output you want. The minus signs in the output are not contributing to the overall size of the output, so they might stick into the margin. As you said you don't need fractions, the following doesn't cover that. It is only working for integer division and always truncates the result. Some portions of the horizontal rules might get drawn twice, that can lead to rendering issues in some PDF viewers, but if you zoom in those should be gone and the print should look fine.

\documentclass[]{article}

\usepackage{xparse,expl3}
\usepackage{mathtools}
\ExplSyntaxOn
\int_new:N \l_Simeon_divisor_int
\int_new:N \l_Simeon_tmpa_int
\int_new:N \l_Simeon_next_dividend_int
\int_new:N \l_Simeon_pops_int
\seq_new:N \l_Simeon_dividend_seq
\seq_new:N \l_Simeon_under_seq
\bool_new:N \l_Simeon_first_bool
\tl_new:N \l_Simeon_tmpa_tl
\msg_new:nnn { Simeon } { empty~arg }%>>>
{
It ~ seems ~ like ~ you ~ provided ~ an ~ empty ~ arg ~ for ~ the ~ #1, ~
this ~ is ~ not ~ allowed.
}%<<<
\cs_new:Npn \Simeon_shift_aux:n #1%>>>
{
\exp_not:n { \phantom { 0 } }
}%<<<
\cs_new:Npn \Simeon_shift:%>>>
{
\int_step_function:nN { \l_Simeon_pops_int } \Simeon_shift_aux:n
}%<<<
\cs_new_protected:Npn \Simeon_array:n #1%>>>
{
\mathllap { \begin { array } { @{} r @{} } #1 \end { array } }
}%<<<
\cs_new_protected:Npn \Simeon_add_to_under:n #1%>>>
{
\seq_put_right:Nx \l_Simeon_under_seq
{
\Simeon_shift:
\Simeon_array:n { #1 }
}
}%<<<
\cs_new_protected:Npn \Simeon_pop_and_calc:nn #1 #2%>>>
{
\seq_pop_left:NN \l_Simeon_dividend_seq \l_Simeon_tmpa_tl
\int_incr:N \l_Simeon_pops_int
\int_set:Nn \l_Simeon_next_dividend_int
{ \l_Simeon_next_dividend_int * 10 + \l_Simeon_tmpa_tl }
\int_set:Nn \l_Simeon_tmpa_int
{
\fp_eval:n
{ trunc ( \l_Simeon_next_dividend_int / \l_Simeon_divisor_int ) }
}
\int_compare:nNnF \l_Simeon_tmpa_int = \c_zero_int
{
#1
\int_set:Nn \l_Simeon_tmpa_int
{ \l_Simeon_tmpa_int * \l_Simeon_divisor_int }
\Simeon_add_to_under:n { #2 }
\int_set:Nn \l_Simeon_next_dividend_int
{ \l_Simeon_next_dividend_int - \l_Simeon_tmpa_int }
}
}%<<<
\cs_new:Npn \Simeon_continue_hline:%>>>
{
\noalign { \vskip -\arrayrulewidth }
\hline
}%<<<
\NewDocumentCommand \longintdiv { m m }%>>>
{
% initializing variables >>>
\tl_if_blank:nT { #1 }
{ \msg_error:nnn { Simeon } { empty~arg } { dividend } }
\tl_if_blank:nT { #2 }
{ \msg_error:nnn { Simeon } { empty~arg } { divisor } }
\seq_set_split:Nnn \l_Simeon_dividend_seq {} { #1 }
\seq_clear:N \l_Simeon_under_seq
\int_set:Nn \l_Simeon_divisor_int { #2 }
\int_zero:N \l_Simeon_next_dividend_int
\int_zero:N \l_Simeon_pops_int
\bool_set_true:N \l_Simeon_first_bool
% <<<
% first division >>>
\bool_do_while:nn
{ \l_Simeon_first_bool && !\seq_if_empty_p:N \l_Simeon_dividend_seq }
{
\Simeon_pop_and_calc:nn { \bool_set_false:N \l_Simeon_first_bool }
{
\exp_not:N \mathllap { {} - {} }
\int_use:N \l_Simeon_tmpa_int
\exp_not:n { \\ \hline }
}
}
% <<<
% other divisions >>>
\bool_while_do:nn { !\seq_if_empty_p:N \l_Simeon_dividend_seq }
{
\Simeon_pop_and_calc:nn {}
{
\exp_not:N \Simeon_continue_hline:
\int_use:N \l_Simeon_next_dividend_int
\exp_not:n { \\ \mathllap { {} - {} } }
\int_use:N \l_Simeon_tmpa_int
\exp_not:n { \\ \hline }
}
}
% <<<
% rest >>>
\Simeon_add_to_under:n
{
\exp_not:N \Simeon_continue_hline:
\int_use:N \l_Simeon_next_dividend_int
}
% <<<
% output >>>
$\begin { array } [ t ] { @{} l @{} } #1 \mathbin{:} #2 = \int_eval:n { \fp_eval:n { trunc ( #1 / #2 ) } }\\ \seq_use:Nn \l_Simeon_under_seq { \\ } \end { array }$
% <<<
}%<<<
\ExplSyntaxOff

\begin{document}
\longintdiv{1011}{11}
\qquad
\longintdiv{3516}{5}
\qquad
\longintdiv{5}{5}
\qquad
\longintdiv{4}{5}
\end{document}


• That's really good! Thank you! Is it possible to make them all on one line? – Simeon Simeonov Nov 18 '18 at 17:46
• @SimeonSimeonov I've cleaned up the code a bit (ignore the %>>> thingies, those are just for me and my VIM). I've also changed the output to be in one line. – Skillmon Nov 18 '18 at 18:13
• REALLY good! Thank you! You saved me hours and many nerves! Great! – Simeon Simeonov Nov 18 '18 at 18:19
• @SimeonSimeonov can you give me the numbers which produce that? – Skillmon Nov 18 '18 at 18:33
• Ahhh sorry. It's working without problems. I had just \begin{spacing}{1.5}. I will close this construction when I am working with it. It was obvious. – Simeon Simeonov Nov 18 '18 at 18:41