Bug Hunting Session
Bug 81267 - Repeat operator
Summary: Repeat operator
Status: NEW
Alias: None
Product: LibreOffice
Classification: Unclassified
Component: Formula Editor (show other bugs)
Version:
(earliest affected)
unspecified
Hardware: Other All
: medium enhancement
Assignee: Not Assigned
URL:
Whiteboard:
Keywords:
Depends on:
Blocks: Formula-Editor
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Reported: 2014-07-12 15:37 UTC by cs
Modified: 2017-07-23 18:50 UTC (History)
0 users

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Description cs 2014-07-12 15:37:49 UTC
I request an enhancement of the formula editor to support the repeat operator using the big R notation proposed by Yingxu Wang. The repeat operator is the mathematical equivalent of a for-loop. It works similar to the summation operator except that the operation can be any mathematical operation. For example, the generalization of the summation operator could be expressed like this:

sum from i = 1 to k x_i = repeat from i = 1 to k "sum"(x_i)

Here "repeat" would render the big R sign similar to the big summation sign.

See for instance:

"On Contemporary Denotational Mathematics for Computational Intelligence" by Yingxu Wang

Any workaround for the current formula editor is welcome for now (how to render a big R).
Comment 1 Owen Genat (retired) 2014-08-01 06:44:01 UTC
(In reply to comment #0)
> I request an enhancement of the formula editor to support the repeat
> operator using the big R notation proposed by Yingxu Wang. 
> ...
> "On Contemporary Denotational Mathematics for Computational Intelligence" by
> Yingxu Wang

This paper can be found here:

http://www.ucalgary.ca/icic/files/icic/36-TCS-2-DM.pdf

There is however no reference to a "repeat operator" in the work. Can you clarify which page in that work and where on the page the operator is indicated. Status set to NEEDINFO. Please set status back to UNCONFIRMED once the requested information is provided. Thanks.
Comment 2 cs 2014-08-13 11:14:25 UTC
(In reply to comment #1)
> This paper can be found here:
> 
> http://www.ucalgary.ca/icic/files/icic/36-TCS-2-DM.pdf
> 
> There is however no reference to a "repeat operator" in the work. Can you
> clarify which page in that work and where on the page the operator is
> indicated. Status set to NEEDINFO. Please set status back to UNCONFIRMED
> once the requested information is provided. Thanks.

Yingxu Wang refer to "The Big-R Notation" in that paper. The definition is in section "2.2.1 The Big-R Notation" (Definition 4) on PDF page 5.

A simple example use case is in section "4.1 The Big-R Notation of RTPA for Modeling Iterative and Recursive System Architectures and Behaviors" (Example 1.) on PDF page 15.

It does not make sense to insert a notation in the Formula Editor. In the Formula Editor, the category "Operators" is where I would expect to find this functionality together with the sum operator.
Comment 3 Owen Genat (retired) 2014-08-18 14:06:39 UTC
(In reply to comment #0)
> I request an enhancement of the formula editor to support the repeat
> operator using the big R notation proposed by Yingxu Wang. ... 
> For example, the generalization of the summation operator could
> be expressed like this:
> 
> sum from i = 1 to k x_i = repeat from i = 1 to k "sum"(x_i)

(In reply to comment #2)
> Yingxu Wang refer to "The Big-R Notation" in that paper. The definition is
> in section "2.2.1 The Big-R Notation" (Definition 4) on PDF page 5.

Thanks for clarifying. The main issue appears to be in relation to setting the R operator (non-italic+bold+size). Apart from this, the two examples on this page can be set using:

oper R from {exp bold{nitalic{font sans BL}} = bold{nitalic{font sans T}}} to bold{nitalic{font sans F}} P newline
oper R from {i bold{nitalic{font sans N}} = 1} to n P(i bold{nitalic{font sans N}})


> A simple example use case is in section "4.1 The Big-R Notation of RTPA for
> Modeling Iterative and Recursive System Architectures and Behaviors"
> (Example 1.) on PDF page 15.

... and the two examples on this page can be set using:

sum from i = 1 to n {x_i} = oper R from nitalic{i} = 1 to n italic{"sum"} ({x_i}) newline
{A_nm} = oper R from nitalic{i} = 0 to n-1 oper R from nitalic{j} = 0 to m-1 A[i,j]bold{nitalic{font sans N}}

There may be a way to set the R operator as required, but I cannot work out how. Confirmed. Status set to NEW.