Iyfjky

Question

I tried to read other topics regarding newcommand* to create a macros in order to have repeated summations with a single command but I was not able to understand the logic behind it.
Let me explain better:
I would like to create a newcommand that simply by typing repsum9Fu, where 9 is the repetition number, can create an output like

F_1u_1+F_2u_2+F_3u_3+...+F_8u_8+F_9u_9.

Can someone help me with this matter? Thank you very much :)

EDIT

Thank you for your answers. I am sorry if I did not post a MWE. The answer provided by current user and zarko does the trick but it uses tikzpicture, while I'd like to use it in Math mode. I'll add an example to show you what I'd like to do (in pseudo code the newcommand)

documentclassarticle
newcommand*repsum[3]{
 for i=1:#1
 if i~=#1
 #2_i#3_i+
 else
 #2_i#3_i
 end
 end
begindocument

The CUF Refined theory expands the summation as

beginequation
u=repsum9Fu=F_tau u_tau
endequation

where the last expression exploits the Einstein notation. 

enddocument

Welcome to TeX.SX! Please help us help you and add a minimal working example (MWE) that illustrates your problem. Reproducing the problem and finding out what the issue is will be much easier when we see compilable code, starting with documentclass... and ending with enddocument. — Sep 5 at 9:56

score 10 · Accepted Answer · 2018-09-05 10:19:30Z

To use it in math mode you could simply use a foreach outside a tikzpicture. This would require the pgffor package (only if you're not using Tikz already):

enter image description here

documentclassarticle

usepackagemathtools
usepackagepgffor

newcommandrepsum[3]%
 foreach i in 1,...,#1
 ifnumi>1
 + #2_i #3_i
 else
 #2_i #3_i
 fi
 


begindocument
 beginequation*
 mathbfFbulletmathbfu = repsum9Fu
 endequation*
enddocument

Thank you, this solved perfectly my issue. Thanks also to the other guy who helped me, probably his answer was not strictly what I wanted because I explained it poorly. For the next time, could you please tell me how to include the output of the code I post? So I can show you directly the expected output I'd like to have. Thank you a lot! — Sep 5 at 10:11
@LMascolo Do you mean how to upload an image? Have a look at this page. At the bottom there is a section on uploading images. — Sep 5 at 10:17
I didn't know it was simply an image, I can do that :) Thank you! — Sep 5 at 10:27

score 7 · Answer 2 · 2018-09-05 10:51:30Z

You can use xparse:

documentclassarticle
usepackageamsmath
usepackagexparse

ExplSyntaxOn
NewDocumentCommandrepsumO3mmm
 % #1 = optional number of starting summands
 % #2 = final number
 % #3 = first symbol
 % #4 = second symbol
 int_step_inline:nn #1 #3sb##1#4sb##1 + 
 dotsb
 int_step_inline:nnn #2 - 1 #2 + #3sb##1#4sb##1 
 
ExplSyntaxOff 

begindocument

First test: $repsum9Fu$

Second test: $repsum[2]6Fu$

The CUF Refined theory expands the summation as
beginequation
u=repsum9Fu=F_tau u_tau
endequation
where the last expression exploits the Einstein notation. 

enddocument

The idea is to make a cycle from 1 to 3 (or the number specified in the optional argument), printing the summands with their subscripts followed by +; then print the dots and + followed by the summands from #2-1 (#2 is the final number of summands) to #2.

With this implementation, you are responsible for ensuring no overlap. So you can do repsum[1]4Fu, but with less than four summands it won't work.

enter image description here

A different version that automatically skips the dots if they're not needed.

documentclassarticle
usepackageamsmath
usepackagexparse

ExplSyntaxOn
NewDocumentCommandrepsumO3mmm
 % #1 = optional number of starting summands
 % #2 = final number
 % #3 = first symbol
 % #4 = second symbol
 int_compare:nTF #2 - #1 < 3 
 % no dots necessary
 #3sb1#4sb1
 int_step_inline:nnn 2 #2 + #3sb##1#4sb##1 
 
 
 int_step_inline:nn #1 #3sb##1#4sb##1 + 
 dotsb
 int_step_inline:nnn #2 - 1 #2 + #3sb##1#4sb##1 
 
 
ExplSyntaxOff 

begindocument

First test: $repsum9Fu$

Second test: $repsum[2]6Fu$

Third test: $repsum5Fu$

Fourth test: $repsum3Fu$

Fifth test: $repsum2Fu$

Sixth test: $repsum1Fu$

The CUF Refined theory expands the summation as
beginequation
u=repsum9Fu=F_tau u_tau
endequation
where the last expression exploits the Einstein notation. 

enddocument

enter image description here

score 3 · Answer 3 · 2018-09-05 10:01:39Z

Maybe this?

documentclassarticle
usepackagetikz
newcommandcussum[1]
 begintikzpicture[baseline=-.1cm]
 foreach x in 1,2,...,#1
 
 ifnumx<#1
 node at (x,0) $F_xu_x+$;
 fi
 ifnumx=#1
 node at (x-.1,0) $F_xu_x$;
 fi
 
 endtikzpicture

begindocument
 cussum9 Minimal Working Examples are nice, aren't they ldots
enddocument

Here is the output:

Screenshot

Ulrich Diez 3,250414 · Answer 4 · 2018-09-05 15:33:36Z

Re-using my replaceiandreplicate-macro from the discussion How to make a command to automate creation of prime factorization-like products?, a possibility of approaching the matter could be:

documentclassarticle

makeatletter
%%=============================================================================
%% Paraphernalia:
%% UD@firstoftwo, UD@secondoftwo,
%% UD@PassFirstToSecond, UD@Exchange, UD@removespace
%% UD@CheckWhetherNull, UD@CheckWhetherBrace,
%% UD@CheckWhetherLeadingSpace, UD@ExtractFirstArg
%%=============================================================================
newcommandUD@firstoftwo[2]#1%
newcommandUD@secondoftwo[2]#2%
newcommandUD@PassFirstToSecond[2]#2#1%
newcommandUD@Exchange[2]#2#1%
newcommandUD@removespaceUD@firstoftwodefUD@removespace %
%%-----------------------------------------------------------------------------
%% Check whether argument is empty:
%%.............................................................................
%% UD@CheckWhetherNull<Argument which is to be checked>%
%% <Tokens to be delivered in case that argument
%% which is to be checked is empty>%
%% <Tokens to be delivered in case that argument
%% which is to be checked is not empty>%
%%
%% The gist of this macro comes from Robert R. Schneck's ifempty-macro:
%% <https://groups.google.com/forum/#!original/comp.text.tex/kuOEIQIrElc/lUg37FmhA74J>
newcommandUD@CheckWhetherNull[1]%
 romannumeral0expandafterUD@secondoftwostringexpandafter
 UD@secondoftwoexpandafterexpandafterstring#1expandafter
 UD@secondoftwostringexpandafterUD@firstoftwoexpandafterexpandafter
 UD@secondoftwostringexpandafterexpandafterUD@firstoftwo %
 UD@secondoftwoexpandafterexpandafterUD@firstoftwo UD@firstoftwo%
%
%%-----------------------------------------------------------------------------
%% Check whether argument's first token is a catcode-1-character
%%.............................................................................
%% UD@CheckWhetherBrace<Argument which is to be checked>%
%% <Tokens to be delivered in case that argument
%% which is to be checked has leading
%% catcode-1-token>%
%% <Tokens to be delivered in case that argument
%% which is to be checked has no leading
%% catcode-1-token>%
newcommandUD@CheckWhetherBrace[1]%
 romannumeral0expandafterUD@secondoftwoexpandafterexpandafter%
 string#1.expandafterUD@firstoftwoexpandafterexpandafter
 UD@secondoftwostringexpandafterexpandafterUD@firstoftwo %
 UD@firstoftwoexpandafterexpandafterUD@firstoftwo UD@secondoftwo%
%
%%-----------------------------------------------------------------------------
%% Check whether brace-balanced argument starts with a space-token
%%.............................................................................
%% UD@CheckWhetherLeadingSpace<Argument which is to be checked>%
%% <Tokens to be delivered in case <argument
%% which is to be checked>'s 1st token is a
%% space-token>%
%% <Tokens to be delivered in case <argument
%% which is to be checked>'s 1st token is not
%% a space-token>%
newcommandUD@CheckWhetherLeadingSpace[1]%
 romannumeral0UD@CheckWhetherNull#1%
 expandafterexpandafterUD@firstoftwo UD@secondoftwo%
 expandafterUD@secondoftwostringUD@CheckWhetherLeadingSpaceB.#1 %
%
newcommandUD@CheckWhetherLeadingSpaceB%
longdefUD@CheckWhetherLeadingSpaceB#1 %
 expandafterUD@CheckWhetherNullexpandafterUD@secondoftwo#1%
 UD@ExchangeUD@firstoftwoUD@ExchangeUD@secondoftwo%
 UD@Exchange expandafterexpandafterexpandafterexpandafter
 expandafterexpandafterexpandafterexpandafterexpandafter
 expandafterexpandafterUD@secondoftwoexpandafterstring%
%
%%-----------------------------------------------------------------------------
%% Extract first inner undelimited argument:
%%
%% UD@ExtractFirstArgABCDE yields A
%%
%% UD@ExtractFirstArgABCDE yields AB
%%.............................................................................
newcommandUD@RemoveTillUD@SelDOm%
longdefUD@RemoveTillUD@SelDOm#1#2UD@SelDOm#1%
newcommandUD@ExtractFirstArg[1]%
 romannumeral0%
 UD@ExtractFirstArgLoop#1UD@SelDOm%
%
newcommandUD@ExtractFirstArgLoop[1]%
 expandafterUD@CheckWhetherNullexpandafterUD@firstoftwo#1%
 #1%
 expandafterUD@ExtractFirstArgLoopexpandafterUD@RemoveTillUD@SelDOm#1%
%
%%=============================================================================
%% DefineReplacementMacro<replacement-macro>%
%% <internal helper-macro>%
%% <item to replace>%
%%
%% defines <replacement-macro> to fetch two arguments,
%% #1 = <replacement for item to replace>
%% #2 = <token sequence with item to replace>
%% , and -- after two expansion-steps to deliver:
%% <token sequence with all instances of <item to replace> replaced 
%% by <replacement for item to replace>. >
%%
%% Internally an <internal helper-macro> is needed.
%%
%% (!!! <replacement-macro> does also replace all pairs of matching 
%% explicit character tokens of catcode 1/2 by matching braces!!!)
%%-----------------------------------------------------------------------------
newcommandDefineReplacementMacro[3]%
 newcommand#2longdef#2##1#3%
 newcommand#1[2]%
 romannumeral0UD@ReplaceAllLoop##2##1#2#3%
 %
%
newcommandUD@ReplaceAllLoop[5]%
 UD@CheckWhetherNull#1 #3%
 UD@CheckWhetherLeadingSpace#1%
 expandafterUD@ReplaceAllLoop
 expandafterUD@removespace#1#2#3 #4#5%
 %
 UD@CheckWhetherBrace#1%
 expandafterexpandafterexpandafterUD@PassFirstToSecond
 expandafterexpandafterexpandafter%
 expandafterUD@PassFirstToSecondexpandafter%
 romannumeral0expandafterUD@ReplaceAllLoop
 romannumeral0UD@ExtractFirstArgLoop#1UD@SelDOm#2#4#5%
 #3%
 expandafterUD@ReplaceAllLoopexpandafterUD@firstoftwo#1#2%
 #4#5%
 %
 expandafterUD@CheckWhetherNoReplacement
 romannumeral0UD@ExtractFirstArgLoop#1UD@SelDOm#1#2#3#4#5%
 %
 %
 %
%
newcommandUD@CheckWhetherNoReplacement[6]%
 expandafterUD@CheckWhetherNullexpandafter#5#1#6%
 %
 expandafterUD@ReplaceAllLoop
 expandafterUD@firstoftwo#2#3#4#1#5#6%
 %
 expandafterUD@ReplaceAllLoop
 expandafterUD@firstoftwo#2#3#4#3#5#6%
 %
%
%%=============================================================================
%% UD@ReplaceAlli -- Replace all "i" in undelimited Argument:
%%
%% UD@ReplaceAlli<replacement for i><token sequence with i>
%% yields <token sequence with all i replaced by replacement for i>
%%
%% <replacement for i> may contain i.
%%
%% (This routine does also replace all pairs of matching explicit 
%% character tokens of catcode 1/2 by matching braces!!!)
%%
%% The letter "i" as item to replace is hard-coded.
%% You cannot replace ÃƒÂ¶etters other than I with this macro.
%%.............................................................................
DefineReplacementMacroUD@ReplaceAlliUD@gobbletoii%
%%
%%=============================================================================
%% replaceiandreplicate<term with i>%
%% <loop-start-index>%
%% <loop-end-index>%
%%
%% e.g., 
%%
%% replaceiandreplicatep_i^epsilon_i13
%%.............................................................................
newcommandreplaceiandreplicate[3]%
 romannumeral0replaceiandreplicateloop#3#2#1%
%
newcommandreplaceiandreplicateloop[4]%
 ifnum#1<#2 %
 expandafterUD@firstoftwo
 else
 expandafterUD@secondoftwo
 fi
 #4%
 expandafterexpandafterexpandafterUD@PassFirstToSecond
 expandafterexpandafterexpandafter%
 UD@ReplaceAlli#1#3#4%
 %
 expandafterreplaceiandreplicateloop
 expandafternumbernumexprnumber#1-1relax#2#3%
 %
 %
%

makeatother

parindent=0ex

begindocument

beginverbatim
$replaceiandreplicateifnum i>1+fi F_iu_i19$
endverbatim

yields:bigskip

$replaceiandreplicateifnum i>1+fi F_iu_i19$


beginverbatim
$csname @gobbleexpandafterexpandafter
 expandafter endcsname
 replaceiandreplicate+F_iu_i19$
endverbatim

yields:bigskip

$csname @gobbleexpandafterexpandafter
 expandafter endcsname
 replaceiandreplicate+F_iu_i19$

enddocument

enter image description here

score 10 · Accepted Answer · 2018-09-05 10:19:30Z

To use it in math mode you could simply use a foreach outside a tikzpicture. This would require the pgffor package (only if you're not using Tikz already):

enter image description here

documentclassarticle

usepackagemathtools
usepackagepgffor

newcommandrepsum[3]%
 foreach i in 1,...,#1
 ifnumi>1
 + #2_i #3_i
 else
 #2_i #3_i
 fi
 


begindocument
 beginequation*
 mathbfFbulletmathbfu = repsum9Fu
 endequation*
enddocument

Thank you, this solved perfectly my issue. Thanks also to the other guy who helped me, probably his answer was not strictly what I wanted because I explained it poorly. For the next time, could you please tell me how to include the output of the code I post? So I can show you directly the expected output I'd like to have. Thank you a lot! — Sep 5 at 10:11
@LMascolo Do you mean how to upload an image? Have a look at this page. At the bottom there is a section on uploading images. — Sep 5 at 10:17
I didn't know it was simply an image, I can do that :) Thank you! — Sep 5 at 10:27

score 7 · Answer 6 · 2018-09-05 10:51:30Z

You can use xparse:

documentclassarticle
usepackageamsmath
usepackagexparse

ExplSyntaxOn
NewDocumentCommandrepsumO3mmm
 % #1 = optional number of starting summands
 % #2 = final number
 % #3 = first symbol
 % #4 = second symbol
 int_step_inline:nn #1 #3sb##1#4sb##1 + 
 dotsb
 int_step_inline:nnn #2 - 1 #2 + #3sb##1#4sb##1 
 
ExplSyntaxOff 

begindocument

First test: $repsum9Fu$

Second test: $repsum[2]6Fu$

The CUF Refined theory expands the summation as
beginequation
u=repsum9Fu=F_tau u_tau
endequation
where the last expression exploits the Einstein notation. 

enddocument

The idea is to make a cycle from 1 to 3 (or the number specified in the optional argument), printing the summands with their subscripts followed by +; then print the dots and + followed by the summands from #2-1 (#2 is the final number of summands) to #2.

With this implementation, you are responsible for ensuring no overlap. So you can do repsum[1]4Fu, but with less than four summands it won't work.

enter image description here

A different version that automatically skips the dots if they're not needed.

documentclassarticle
usepackageamsmath
usepackagexparse

ExplSyntaxOn
NewDocumentCommandrepsumO3mmm
 % #1 = optional number of starting summands
 % #2 = final number
 % #3 = first symbol
 % #4 = second symbol
 int_compare:nTF #2 - #1 < 3 
 % no dots necessary
 #3sb1#4sb1
 int_step_inline:nnn 2 #2 + #3sb##1#4sb##1 
 
 
 int_step_inline:nn #1 #3sb##1#4sb##1 + 
 dotsb
 int_step_inline:nnn #2 - 1 #2 + #3sb##1#4sb##1 
 
 
ExplSyntaxOff 

begindocument

First test: $repsum9Fu$

Second test: $repsum[2]6Fu$

Third test: $repsum5Fu$

Fourth test: $repsum3Fu$

Fifth test: $repsum2Fu$

Sixth test: $repsum1Fu$

The CUF Refined theory expands the summation as
beginequation
u=repsum9Fu=F_tau u_tau
endequation
where the last expression exploits the Einstein notation. 

enddocument

enter image description here

score 3 · Answer 7 · 2018-09-05 10:01:39Z

Maybe this?

documentclassarticle
usepackagetikz
newcommandcussum[1]
 begintikzpicture[baseline=-.1cm]
 foreach x in 1,2,...,#1
 
 ifnumx<#1
 node at (x,0) $F_xu_x+$;
 fi
 ifnumx=#1
 node at (x-.1,0) $F_xu_x$;
 fi
 
 endtikzpicture

begindocument
 cussum9 Minimal Working Examples are nice, aren't they ldots
enddocument

Here is the output:

Screenshot

Ulrich Diez 3,250414 · Answer 8 · 2018-09-05 15:33:36Z

Re-using my replaceiandreplicate-macro from the discussion How to make a command to automate creation of prime factorization-like products?, a possibility of approaching the matter could be:

documentclassarticle

makeatletter
%%=============================================================================
%% Paraphernalia:
%% UD@firstoftwo, UD@secondoftwo,
%% UD@PassFirstToSecond, UD@Exchange, UD@removespace
%% UD@CheckWhetherNull, UD@CheckWhetherBrace,
%% UD@CheckWhetherLeadingSpace, UD@ExtractFirstArg
%%=============================================================================
newcommandUD@firstoftwo[2]#1%
newcommandUD@secondoftwo[2]#2%
newcommandUD@PassFirstToSecond[2]#2#1%
newcommandUD@Exchange[2]#2#1%
newcommandUD@removespaceUD@firstoftwodefUD@removespace %
%%-----------------------------------------------------------------------------
%% Check whether argument is empty:
%%.............................................................................
%% UD@CheckWhetherNull<Argument which is to be checked>%
%% <Tokens to be delivered in case that argument
%% which is to be checked is empty>%
%% <Tokens to be delivered in case that argument
%% which is to be checked is not empty>%
%%
%% The gist of this macro comes from Robert R. Schneck's ifempty-macro:
%% <https://groups.google.com/forum/#!original/comp.text.tex/kuOEIQIrElc/lUg37FmhA74J>
newcommandUD@CheckWhetherNull[1]%
 romannumeral0expandafterUD@secondoftwostringexpandafter
 UD@secondoftwoexpandafterexpandafterstring#1expandafter
 UD@secondoftwostringexpandafterUD@firstoftwoexpandafterexpandafter
 UD@secondoftwostringexpandafterexpandafterUD@firstoftwo %
 UD@secondoftwoexpandafterexpandafterUD@firstoftwo UD@firstoftwo%
%
%%-----------------------------------------------------------------------------
%% Check whether argument's first token is a catcode-1-character
%%.............................................................................
%% UD@CheckWhetherBrace<Argument which is to be checked>%
%% <Tokens to be delivered in case that argument
%% which is to be checked has leading
%% catcode-1-token>%
%% <Tokens to be delivered in case that argument
%% which is to be checked has no leading
%% catcode-1-token>%
newcommandUD@CheckWhetherBrace[1]%
 romannumeral0expandafterUD@secondoftwoexpandafterexpandafter%
 string#1.expandafterUD@firstoftwoexpandafterexpandafter
 UD@secondoftwostringexpandafterexpandafterUD@firstoftwo %
 UD@firstoftwoexpandafterexpandafterUD@firstoftwo UD@secondoftwo%
%
%%-----------------------------------------------------------------------------
%% Check whether brace-balanced argument starts with a space-token
%%.............................................................................
%% UD@CheckWhetherLeadingSpace<Argument which is to be checked>%
%% <Tokens to be delivered in case <argument
%% which is to be checked>'s 1st token is a
%% space-token>%
%% <Tokens to be delivered in case <argument
%% which is to be checked>'s 1st token is not
%% a space-token>%
newcommandUD@CheckWhetherLeadingSpace[1]%
 romannumeral0UD@CheckWhetherNull#1%
 expandafterexpandafterUD@firstoftwo UD@secondoftwo%
 expandafterUD@secondoftwostringUD@CheckWhetherLeadingSpaceB.#1 %
%
newcommandUD@CheckWhetherLeadingSpaceB%
longdefUD@CheckWhetherLeadingSpaceB#1 %
 expandafterUD@CheckWhetherNullexpandafterUD@secondoftwo#1%
 UD@ExchangeUD@firstoftwoUD@ExchangeUD@secondoftwo%
 UD@Exchange expandafterexpandafterexpandafterexpandafter
 expandafterexpandafterexpandafterexpandafterexpandafter
 expandafterexpandafterUD@secondoftwoexpandafterstring%
%
%%-----------------------------------------------------------------------------
%% Extract first inner undelimited argument:
%%
%% UD@ExtractFirstArgABCDE yields A
%%
%% UD@ExtractFirstArgABCDE yields AB
%%.............................................................................
newcommandUD@RemoveTillUD@SelDOm%
longdefUD@RemoveTillUD@SelDOm#1#2UD@SelDOm#1%
newcommandUD@ExtractFirstArg[1]%
 romannumeral0%
 UD@ExtractFirstArgLoop#1UD@SelDOm%
%
newcommandUD@ExtractFirstArgLoop[1]%
 expandafterUD@CheckWhetherNullexpandafterUD@firstoftwo#1%
 #1%
 expandafterUD@ExtractFirstArgLoopexpandafterUD@RemoveTillUD@SelDOm#1%
%
%%=============================================================================
%% DefineReplacementMacro<replacement-macro>%
%% <internal helper-macro>%
%% <item to replace>%
%%
%% defines <replacement-macro> to fetch two arguments,
%% #1 = <replacement for item to replace>
%% #2 = <token sequence with item to replace>
%% , and -- after two expansion-steps to deliver:
%% <token sequence with all instances of <item to replace> replaced 
%% by <replacement for item to replace>. >
%%
%% Internally an <internal helper-macro> is needed.
%%
%% (!!! <replacement-macro> does also replace all pairs of matching 
%% explicit character tokens of catcode 1/2 by matching braces!!!)
%%-----------------------------------------------------------------------------
newcommandDefineReplacementMacro[3]%
 newcommand#2longdef#2##1#3%
 newcommand#1[2]%
 romannumeral0UD@ReplaceAllLoop##2##1#2#3%
 %
%
newcommandUD@ReplaceAllLoop[5]%
 UD@CheckWhetherNull#1 #3%
 UD@CheckWhetherLeadingSpace#1%
 expandafterUD@ReplaceAllLoop
 expandafterUD@removespace#1#2#3 #4#5%
 %
 UD@CheckWhetherBrace#1%
 expandafterexpandafterexpandafterUD@PassFirstToSecond
 expandafterexpandafterexpandafter%
 expandafterUD@PassFirstToSecondexpandafter%
 romannumeral0expandafterUD@ReplaceAllLoop
 romannumeral0UD@ExtractFirstArgLoop#1UD@SelDOm#2#4#5%
 #3%
 expandafterUD@ReplaceAllLoopexpandafterUD@firstoftwo#1#2%
 #4#5%
 %
 expandafterUD@CheckWhetherNoReplacement
 romannumeral0UD@ExtractFirstArgLoop#1UD@SelDOm#1#2#3#4#5%
 %
 %
 %
%
newcommandUD@CheckWhetherNoReplacement[6]%
 expandafterUD@CheckWhetherNullexpandafter#5#1#6%
 %
 expandafterUD@ReplaceAllLoop
 expandafterUD@firstoftwo#2#3#4#1#5#6%
 %
 expandafterUD@ReplaceAllLoop
 expandafterUD@firstoftwo#2#3#4#3#5#6%
 %
%
%%=============================================================================
%% UD@ReplaceAlli -- Replace all "i" in undelimited Argument:
%%
%% UD@ReplaceAlli<replacement for i><token sequence with i>
%% yields <token sequence with all i replaced by replacement for i>
%%
%% <replacement for i> may contain i.
%%
%% (This routine does also replace all pairs of matching explicit 
%% character tokens of catcode 1/2 by matching braces!!!)
%%
%% The letter "i" as item to replace is hard-coded.
%% You cannot replace ÃƒÂ¶etters other than I with this macro.
%%.............................................................................
DefineReplacementMacroUD@ReplaceAlliUD@gobbletoii%
%%
%%=============================================================================
%% replaceiandreplicate<term with i>%
%% <loop-start-index>%
%% <loop-end-index>%
%%
%% e.g., 
%%
%% replaceiandreplicatep_i^epsilon_i13
%%.............................................................................
newcommandreplaceiandreplicate[3]%
 romannumeral0replaceiandreplicateloop#3#2#1%
%
newcommandreplaceiandreplicateloop[4]%
 ifnum#1<#2 %
 expandafterUD@firstoftwo
 else
 expandafterUD@secondoftwo
 fi
 #4%
 expandafterexpandafterexpandafterUD@PassFirstToSecond
 expandafterexpandafterexpandafter%
 UD@ReplaceAlli#1#3#4%
 %
 expandafterreplaceiandreplicateloop
 expandafternumbernumexprnumber#1-1relax#2#3%
 %
 %
%

makeatother

parindent=0ex

begindocument

beginverbatim
$replaceiandreplicateifnum i>1+fi F_iu_i19$
endverbatim

yields:bigskip

$replaceiandreplicateifnum i>1+fi F_iu_i19$


beginverbatim
$csname @gobbleexpandafterexpandafter
 expandafter endcsname
 replaceiandreplicate+F_iu_i19$
endverbatim

yields:bigskip

$csname @gobbleexpandafterexpandafter
 expandafter endcsname
 replaceiandreplicate+F_iu_i19$

enddocument

enter image description here

Search This Blog

Iyfjky

Loop code for repeated sums

4 Answers
4

Your Answer

Post as a guest

4 Answers
4

4 Answers
4

Post as a guest

Comments

Post a Comment

Popular posts from this blog

What does second last employer means? [closed]

List of Gilmore Girls characters

Confectionery

Category

Random preview

Loop code for repeated sums

4 Answers 4

Your Answer

Sign up or log in

Post as a guest

Post as a guest

4 Answers 4

4 Answers 4

Sign up or log in

Post as a guest

Post as a guest

Sign up or log in

Post as a guest

Sign up or log in

Post as a guest

Sign up or log in

Post as a guest

Comments

Post a Comment

Popular posts from this blog

What does second last employer means? [closed]

List of Gilmore Girls characters

Confectionery

4 Answers
4

4 Answers
4

4 Answers
4