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3

The function I'm trying to create is one that takes two numbers and prints the result with some math. The following is my code:

documentclass[12pt,a4paper]{article}



begin{document}

    directlua{

        function prod(a,b)

            tex.print(a "$times$" b "$=$" a*c)

        end

    }



    The product of 2 and 3: directlua{prod(2,3)}.

end{document}

I can't make it print the whole statement correctly. How to solve it?

luatex calculations

share|improve this question

edited 13 mins ago

Mico

285k31388778

asked 1 hour ago

LevyLevy

437312

• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  Try tex.print("$" .. a .. "string\times" .. b .. "=" .. a*b .. "$")
  
  – moewe
  59 mins ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Unlike TeX, to which everything is (by default) a token to be typeset so you can simply write "hello world" and have those words appear in the typeset output, Lua is a general-purpose programming language in which something like a b is a syntax error (assuming a and b are variables). Here, tex.print is a Lua function that takes a single string as input, so you need to give it a single string. (There are other forms of tex.print too, that you can read in the LuaTeX manual, but those are probably not what you want.) Lua uses .. to concatenate strings.
  
  – ShreevatsaR
  52 mins ago
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  BTW instead of concatenating different strings with .., you can also use string.format to build a string, e.g. in a file test.lua put function prod(a,b) tex.print(string.format([[$%d times %d = %d$]], a, b, a*b)) end and in your file do directlua{dofile('test.lua')} -- here the [[ instead of " is to avoid needing to escape the backslash in times.
  
  – ShreevatsaR
  45 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @ShreevatsaR Thanks for that option!
  
  – Levy
  21 mins ago
  

  
  
  
  

add a comment | 

3

The function I'm trying to create is one that takes two numbers and prints the result with some math. The following is my code:

documentclass[12pt,a4paper]{article}



begin{document}

    directlua{

        function prod(a,b)

            tex.print(a "$times$" b "$=$" a*c)

        end

    }



    The product of 2 and 3: directlua{prod(2,3)}.

end{document}

I can't make it print the whole statement correctly. How to solve it?

luatex calculations

share|improve this question

edited 13 mins ago

Mico

285k31388778

asked 1 hour ago

LevyLevy

437312

• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  Try tex.print("$" .. a .. "string\times" .. b .. "=" .. a*b .. "$")
  
  – moewe
  59 mins ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Unlike TeX, to which everything is (by default) a token to be typeset so you can simply write "hello world" and have those words appear in the typeset output, Lua is a general-purpose programming language in which something like a b is a syntax error (assuming a and b are variables). Here, tex.print is a Lua function that takes a single string as input, so you need to give it a single string. (There are other forms of tex.print too, that you can read in the LuaTeX manual, but those are probably not what you want.) Lua uses .. to concatenate strings.
  
  – ShreevatsaR
  52 mins ago
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  BTW instead of concatenating different strings with .., you can also use string.format to build a string, e.g. in a file test.lua put function prod(a,b) tex.print(string.format([[$%d times %d = %d$]], a, b, a*b)) end and in your file do directlua{dofile('test.lua')} -- here the [[ instead of " is to avoid needing to escape the backslash in times.
  
  – ShreevatsaR
  45 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @ShreevatsaR Thanks for that option!
  
  – Levy
  21 mins ago
  

  
  
  
  

add a comment | 

The function I'm trying to create is one that takes two numbers and prints the result with some math. The following is my code:

documentclass[12pt,a4paper]{article}



begin{document}

    directlua{

        function prod(a,b)

            tex.print(a "$times$" b "$=$" a*c)

        end

    }



    The product of 2 and 3: directlua{prod(2,3)}.

end{document}

I can't make it print the whole statement correctly. How to solve it?

luatex calculations

share|improve this question

edited 13 mins ago

Mico

285k31388778

asked 1 hour ago

LevyLevy

437312

documentclass[12pt,a4paper]{article}



begin{document}

    directlua{

        function prod(a,b)

            tex.print(a "$times$" b "$=$" a*c)

        end

    }



    The product of 2 and 3: directlua{prod(2,3)}.

end{document}

share|improve this question

edited 13 mins ago

Mico

285k31388778

asked 1 hour ago

LevyLevy

437312

share|improve this question

edited 13 mins ago

Mico

285k31388778

asked 1 hour ago

LevyLevy

437312

edited 13 mins ago

Mico

285k31388778

edited 13 mins ago

Mico

285k31388778

asked 1 hour ago

LevyLevy

437312

asked 1 hour ago

LevyLevy

437312

3 Answers
3

active

oldest

votes

5

documentclass[12pt,a4paper]{article}



directlua{

  function prod(a,b)

    tex.print("$" .. a .. "string\times" .. b .. "=" ..  a*b .. "$")

  end

}



begin{document}    

  The product of 2 and 3: directlua{prod(2,3)}.

end{document}

One tricky thing is getting the backslash escaping game right: LuaTeX: How to handle a Lua function that prints TeX macros. directlua expands macros before passing them on to Lua, so times gets messed up. But something like stringtimes, which should stop that expansion does not quite work as intended because t is a special escape for the tab in Lua. Hence we need to escape the backslash there. In Lua you would have to type \times, but in TeX we need to stop the \ from being expanded, so we need string\times. That is one of the reasons why it is often recommended to use the luacode package or externalise Lua functions into their own .lua files and then load them with dofile or require (see for example How to do a 'printline' in LuaTeX, a bit on dofile and require can be found at LuaLatex: Difference between `dofile` and `require` when loading lua files).

Another thing is that you need .. to concatenate strings.

Finally, you probably want the entire expression in math mode and not just certain bits.

Also moved the directlua function definition into the preamble. (Thanks to Mico for the suggestion.)

share|improve this answer

edited 27 mins ago

answered 57 mins ago

moewemoewe

96.2k10117360

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  That's what I was looking for. It worked here. Thank you!
  
  – Levy
  51 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  And the explanation was really helpful!
  
  – Levy
  51 mins ago
  

  
  
  
  

add a comment | 

4

documentclass[12pt,a4paper]{article}



begin{document}

    directlua{

        function prod(a,b)

            tex.print(a.. "$string\times$".. b.. "$=$".. a*b)

        end

    }



    The product of 2 and 3: directlua{prod(2,3)}.

end{document}

share|improve this answer

answered 57 mins ago

Ulrike FischerUlrike Fischer

198k9305692

add a comment | 

2

Just for completeness, here's a solution that shows how to (a) write the Lua code to an external file, (b) load the Luacode via a directlua{dofile("...")} directive, and (c) set up a LaTeX "wrapper" macro (called showprod in the example below) whose function (pun intended) is to invoke the Lua function.

Note that with this setup, one can write \ rather than string\ to denote a single backslash character. (This is also the case for the luacode and luacode* environments that are provided by the luacode package.)

RequirePackage{filecontents}

begin{filecontents*}{show_prod.lua}

function show_prod ( a , b )

  tex.sprint ( "$"..a.."\times"..b.."="..a*b.."$" )

end

end{filecontents*}



documentclass{article}

%% Load Lua code from external file and define a LaTeX "wrapper" macro

directlua{dofile("show_prod.lua")}

newcommandshowprod[2]{directlua{show_prod(#1,#2)}}



begin{document}

The product of 2 and 3: showprod{2}{3}.

end{document}

share|improve this answer

answered 17 mins ago

MicoMico

285k31388778

add a comment | 

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5

documentclass[12pt,a4paper]{article}



directlua{

  function prod(a,b)

    tex.print("$" .. a .. "string\times" .. b .. "=" ..  a*b .. "$")

  end

}



begin{document}    

  The product of 2 and 3: directlua{prod(2,3)}.

end{document}

One tricky thing is getting the backslash escaping game right: LuaTeX: How to handle a Lua function that prints TeX macros. directlua expands macros before passing them on to Lua, so times gets messed up. But something like stringtimes, which should stop that expansion does not quite work as intended because t is a special escape for the tab in Lua. Hence we need to escape the backslash there. In Lua you would have to type \times, but in TeX we need to stop the \ from being expanded, so we need string\times. That is one of the reasons why it is often recommended to use the luacode package or externalise Lua functions into their own .lua files and then load them with dofile or require (see for example How to do a 'printline' in LuaTeX, a bit on dofile and require can be found at LuaLatex: Difference between `dofile` and `require` when loading lua files).

Another thing is that you need .. to concatenate strings.

Finally, you probably want the entire expression in math mode and not just certain bits.

Also moved the directlua function definition into the preamble. (Thanks to Mico for the suggestion.)

share|improve this answer

edited 27 mins ago

answered 57 mins ago

moewemoewe

96.2k10117360

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  That's what I was looking for. It worked here. Thank you!
  
  – Levy
  51 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  And the explanation was really helpful!
  
  – Levy
  51 mins ago
  

  
  
  
  

add a comment | 

5

documentclass[12pt,a4paper]{article}



directlua{

  function prod(a,b)

    tex.print("$" .. a .. "string\times" .. b .. "=" ..  a*b .. "$")

  end

}



begin{document}    

  The product of 2 and 3: directlua{prod(2,3)}.

end{document}

One tricky thing is getting the backslash escaping game right: LuaTeX: How to handle a Lua function that prints TeX macros. directlua expands macros before passing them on to Lua, so times gets messed up. But something like stringtimes, which should stop that expansion does not quite work as intended because t is a special escape for the tab in Lua. Hence we need to escape the backslash there. In Lua you would have to type \times, but in TeX we need to stop the \ from being expanded, so we need string\times. That is one of the reasons why it is often recommended to use the luacode package or externalise Lua functions into their own .lua files and then load them with dofile or require (see for example How to do a 'printline' in LuaTeX, a bit on dofile and require can be found at LuaLatex: Difference between `dofile` and `require` when loading lua files).

Another thing is that you need .. to concatenate strings.

Finally, you probably want the entire expression in math mode and not just certain bits.

Also moved the directlua function definition into the preamble. (Thanks to Mico for the suggestion.)

share|improve this answer

edited 27 mins ago

answered 57 mins ago

moewemoewe

96.2k10117360

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  That's what I was looking for. It worked here. Thank you!
  
  – Levy
  51 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  And the explanation was really helpful!
  
  – Levy
  51 mins ago
  

  
  
  
  

add a comment | 

documentclass[12pt,a4paper]{article}



directlua{

  function prod(a,b)

    tex.print("$" .. a .. "string\times" .. b .. "=" ..  a*b .. "$")

  end

}



begin{document}    

  The product of 2 and 3: directlua{prod(2,3)}.

end{document}

One tricky thing is getting the backslash escaping game right: LuaTeX: How to handle a Lua function that prints TeX macros. directlua expands macros before passing them on to Lua, so times gets messed up. But something like stringtimes, which should stop that expansion does not quite work as intended because t is a special escape for the tab in Lua. Hence we need to escape the backslash there. In Lua you would have to type \times, but in TeX we need to stop the \ from being expanded, so we need string\times. That is one of the reasons why it is often recommended to use the luacode package or externalise Lua functions into their own .lua files and then load them with dofile or require (see for example How to do a 'printline' in LuaTeX, a bit on dofile and require can be found at LuaLatex: Difference between `dofile` and `require` when loading lua files).

Another thing is that you need .. to concatenate strings.

Finally, you probably want the entire expression in math mode and not just certain bits.

Also moved the directlua function definition into the preamble. (Thanks to Mico for the suggestion.)

share|improve this answer

edited 27 mins ago

answered 57 mins ago

moewemoewe

96.2k10117360

documentclass[12pt,a4paper]{article}



directlua{

  function prod(a,b)

    tex.print("$" .. a .. "string\times" .. b .. "=" ..  a*b .. "$")

  end

}



begin{document}    

  The product of 2 and 3: directlua{prod(2,3)}.

end{document}

share|improve this answer

edited 27 mins ago

answered 57 mins ago

moewemoewe

96.2k10117360

answered 57 mins ago

moewemoewe

96.2k10117360

answered 57 mins ago

moewemoewe

96.2k10117360

4

documentclass[12pt,a4paper]{article}



begin{document}

    directlua{

        function prod(a,b)

            tex.print(a.. "$string\times$".. b.. "$=$".. a*b)

        end

    }



    The product of 2 and 3: directlua{prod(2,3)}.

end{document}

share|improve this answer

answered 57 mins ago

Ulrike FischerUlrike Fischer

198k9305692

add a comment | 

4

documentclass[12pt,a4paper]{article}



begin{document}

    directlua{

        function prod(a,b)

            tex.print(a.. "$string\times$".. b.. "$=$".. a*b)

        end

    }



    The product of 2 and 3: directlua{prod(2,3)}.

end{document}

share|improve this answer

answered 57 mins ago

Ulrike FischerUlrike Fischer

198k9305692

add a comment | 

documentclass[12pt,a4paper]{article}



begin{document}

    directlua{

        function prod(a,b)

            tex.print(a.. "$string\times$".. b.. "$=$".. a*b)

        end

    }



    The product of 2 and 3: directlua{prod(2,3)}.

end{document}

share|improve this answer

answered 57 mins ago

Ulrike FischerUlrike Fischer

198k9305692

documentclass[12pt,a4paper]{article}



begin{document}

    directlua{

        function prod(a,b)

            tex.print(a.. "$string\times$".. b.. "$=$".. a*b)

        end

    }



    The product of 2 and 3: directlua{prod(2,3)}.

end{document}

share|improve this answer

answered 57 mins ago

Ulrike FischerUlrike Fischer

198k9305692

answered 57 mins ago

Ulrike FischerUlrike Fischer

198k9305692

answered 57 mins ago

Ulrike FischerUlrike Fischer

198k9305692

2

Just for completeness, here's a solution that shows how to (a) write the Lua code to an external file, (b) load the Luacode via a directlua{dofile("...")} directive, and (c) set up a LaTeX "wrapper" macro (called showprod in the example below) whose function (pun intended) is to invoke the Lua function.

Note that with this setup, one can write \ rather than string\ to denote a single backslash character. (This is also the case for the luacode and luacode* environments that are provided by the luacode package.)

RequirePackage{filecontents}

begin{filecontents*}{show_prod.lua}

function show_prod ( a , b )

  tex.sprint ( "$"..a.."\times"..b.."="..a*b.."$" )

end

end{filecontents*}



documentclass{article}

%% Load Lua code from external file and define a LaTeX "wrapper" macro

directlua{dofile("show_prod.lua")}

newcommandshowprod[2]{directlua{show_prod(#1,#2)}}



begin{document}

The product of 2 and 3: showprod{2}{3}.

end{document}

share|improve this answer

answered 17 mins ago

MicoMico

285k31388778

add a comment | 

2

Just for completeness, here's a solution that shows how to (a) write the Lua code to an external file, (b) load the Luacode via a directlua{dofile("...")} directive, and (c) set up a LaTeX "wrapper" macro (called showprod in the example below) whose function (pun intended) is to invoke the Lua function.

Note that with this setup, one can write \ rather than string\ to denote a single backslash character. (This is also the case for the luacode and luacode* environments that are provided by the luacode package.)

RequirePackage{filecontents}

begin{filecontents*}{show_prod.lua}

function show_prod ( a , b )

  tex.sprint ( "$"..a.."\times"..b.."="..a*b.."$" )

end

end{filecontents*}



documentclass{article}

%% Load Lua code from external file and define a LaTeX "wrapper" macro

directlua{dofile("show_prod.lua")}

newcommandshowprod[2]{directlua{show_prod(#1,#2)}}



begin{document}

The product of 2 and 3: showprod{2}{3}.

end{document}

share|improve this answer

answered 17 mins ago

MicoMico

285k31388778

add a comment | 

Just for completeness, here's a solution that shows how to (a) write the Lua code to an external file, (b) load the Luacode via a directlua{dofile("...")} directive, and (c) set up a LaTeX "wrapper" macro (called showprod in the example below) whose function (pun intended) is to invoke the Lua function.

Note that with this setup, one can write \ rather than string\ to denote a single backslash character. (This is also the case for the luacode and luacode* environments that are provided by the luacode package.)

RequirePackage{filecontents}

begin{filecontents*}{show_prod.lua}

function show_prod ( a , b )

  tex.sprint ( "$"..a.."\times"..b.."="..a*b.."$" )

end

end{filecontents*}



documentclass{article}

%% Load Lua code from external file and define a LaTeX "wrapper" macro

directlua{dofile("show_prod.lua")}

newcommandshowprod[2]{directlua{show_prod(#1,#2)}}



begin{document}

The product of 2 and 3: showprod{2}{3}.

end{document}

share|improve this answer

answered 17 mins ago

MicoMico

285k31388778

RequirePackage{filecontents}

begin{filecontents*}{show_prod.lua}

function show_prod ( a , b )

  tex.sprint ( "$"..a.."\times"..b.."="..a*b.."$" )

end

end{filecontents*}



documentclass{article}

%% Load Lua code from external file and define a LaTeX "wrapper" macro

directlua{dofile("show_prod.lua")}

newcommandshowprod[2]{directlua{show_prod(#1,#2)}}



begin{document}

The product of 2 and 3: showprod{2}{3}.

end{document}

share|improve this answer

answered 17 mins ago

MicoMico

285k31388778

answered 17 mins ago

MicoMico

285k31388778

answered 17 mins ago

MicoMico

285k31388778