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2

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

begindocument
 directlua
 function prod(a,b)
 tex.print(a "$times$" b "$=$" a*c)
 end
 

 The product of 2 and 3: directluaprod(2,3).
enddocument

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

luatex

share|improve this question

asked 48 mins ago

LevyLevy

432312

• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  Try tex.print("$" .. a .. "string\times" .. b .. "=" .. a*b .. "$")
  
  – moewe
  38 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
  31 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 directluadofile('test.lua') -- here the [[ instead of " is to avoid needing to escape the backslash in times.
  
  – ShreevatsaR
  24 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @ShreevatsaR Thanks for that option!
  
  – Levy
  1 min ago
  

  
  
  
  

add a comment | 

2

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

begindocument
 directlua
 function prod(a,b)
 tex.print(a "$times$" b "$=$" a*c)
 end
 

 The product of 2 and 3: directluaprod(2,3).
enddocument

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

luatex

share|improve this question

asked 48 mins ago

LevyLevy

432312

• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  Try tex.print("$" .. a .. "string\times" .. b .. "=" .. a*b .. "$")
  
  – moewe
  38 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
  31 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 directluadofile('test.lua') -- here the [[ instead of " is to avoid needing to escape the backslash in times.
  
  – ShreevatsaR
  24 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @ShreevatsaR Thanks for that option!
  
  – Levy
  1 min 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

begindocument
 directlua
 function prod(a,b)
 tex.print(a "$times$" b "$=$" a*c)
 end
 

 The product of 2 and 3: directluaprod(2,3).
enddocument

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

luatex

share|improve this question

asked 48 mins ago

LevyLevy

432312

documentclass[12pt,a4paper]article

begindocument
 directlua
 function prod(a,b)
 tex.print(a "$times$" b "$=$" a*c)
 end
 

 The product of 2 and 3: directluaprod(2,3).
enddocument

share|improve this question

asked 48 mins ago

LevyLevy

432312

share|improve this question

asked 48 mins ago

LevyLevy

432312

asked 48 mins ago

LevyLevy

432312

asked 48 mins ago

LevyLevy

432312

2 Answers
2

active

oldest

votes

5

documentclass[12pt,a4paper]article

directlua
 function prod(a,b)
 tex.print("$" .. a .. "string\times" .. b .. "=" .. a*b .. "$")
 end


begindocument 
 The product of 2 and 3: directluaprod(2,3).
enddocument

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 6 mins ago

answered 36 mins ago

moewemoewe

96.2k10117360

• 
  
  
  

  
  

  
  
  
  
  
  

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

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

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

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Mico Done. Thanks for the idea.
  
  – moewe
  6 mins ago
  

  
  
  
  

add a comment | 

4

documentclass[12pt,a4paper]article

begindocument
 directlua
 function prod(a,b)
 tex.print(a.. "$string\times$".. b.. "$=$".. a*b)
 end
 

 The product of 2 and 3: directluaprod(2,3).
enddocument

share|improve this answer

answered 37 mins ago

Ulrike FischerUlrike Fischer

198k9305692

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


begindocument 
 The product of 2 and 3: directluaprod(2,3).
enddocument

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 6 mins ago

answered 36 mins ago

moewemoewe

96.2k10117360

• 
  
  
  

  
  

  
  
  
  
  
  

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

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

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

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Mico Done. Thanks for the idea.
  
  – moewe
  6 mins ago
  

  
  
  
  

add a comment | 

5

documentclass[12pt,a4paper]article

directlua
 function prod(a,b)
 tex.print("$" .. a .. "string\times" .. b .. "=" .. a*b .. "$")
 end


begindocument 
 The product of 2 and 3: directluaprod(2,3).
enddocument

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 6 mins ago

answered 36 mins ago

moewemoewe

96.2k10117360

• 
  
  
  

  
  

  
  
  
  
  
  

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

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

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

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Mico Done. Thanks for the idea.
  
  – moewe
  6 mins ago
  

  
  
  
  

add a comment | 

documentclass[12pt,a4paper]article

directlua
 function prod(a,b)
 tex.print("$" .. a .. "string\times" .. b .. "=" .. a*b .. "$")
 end


begindocument 
 The product of 2 and 3: directluaprod(2,3).
enddocument

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 6 mins ago

answered 36 mins ago

moewemoewe

96.2k10117360

documentclass[12pt,a4paper]article

directlua
 function prod(a,b)
 tex.print("$" .. a .. "string\times" .. b .. "=" .. a*b .. "$")
 end


begindocument 
 The product of 2 and 3: directluaprod(2,3).
enddocument

share|improve this answer

edited 6 mins ago

answered 36 mins ago

moewemoewe

96.2k10117360

answered 36 mins ago

moewemoewe

96.2k10117360

answered 36 mins ago

moewemoewe

96.2k10117360

4

documentclass[12pt,a4paper]article

begindocument
 directlua
 function prod(a,b)
 tex.print(a.. "$string\times$".. b.. "$=$".. a*b)
 end
 

 The product of 2 and 3: directluaprod(2,3).
enddocument

share|improve this answer

answered 37 mins ago

Ulrike FischerUlrike Fischer

198k9305692

add a comment | 

4

documentclass[12pt,a4paper]article

begindocument
 directlua
 function prod(a,b)
 tex.print(a.. "$string\times$".. b.. "$=$".. a*b)
 end
 

 The product of 2 and 3: directluaprod(2,3).
enddocument

share|improve this answer

answered 37 mins ago

Ulrike FischerUlrike Fischer

198k9305692

add a comment | 

documentclass[12pt,a4paper]article

begindocument
 directlua
 function prod(a,b)
 tex.print(a.. "$string\times$".. b.. "$=$".. a*b)
 end
 

 The product of 2 and 3: directluaprod(2,3).
enddocument

share|improve this answer

answered 37 mins ago

Ulrike FischerUlrike Fischer

198k9305692

documentclass[12pt,a4paper]article

begindocument
 directlua
 function prod(a,b)
 tex.print(a.. "$string\times$".. b.. "$=$".. a*b)
 end
 

 The product of 2 and 3: directluaprod(2,3).
enddocument

share|improve this answer

answered 37 mins ago

Ulrike FischerUlrike Fischer

198k9305692

answered 37 mins ago

Ulrike FischerUlrike Fischer

198k9305692

answered 37 mins ago

Ulrike FischerUlrike Fischer

198k9305692