Testwiki:Reference desk/Archives/Computing/2017 April 8

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April 8

Qudratic Equations - Promise Problem

Is the follwing promise problem NP-complete?

Input: a system of quadratic equations with either one or zero solutions.

Question: does the system have a solution? 31.154.81.31 (talk) 06:56, 8 April 2017 (UTC)

A system of N quadratic equations potentially has $2^N$ solutions. Please, clarify your question. Ruslik_Zero 20:50, 8 April 2017 (UTC)

The question seems to me to be well defined: Given a system that is known to have at most one solution, how hard is it to determine whether there is one? —Tamfang (talk) 08:30, 10 April 2017 (UTC)

A spreadsheet question

In a spreadsheet, is there a way to format a cell so that when you click it, it brings you to the what is in the cell? I mean, if cell A1 contains "=A3", I would like to be able to click A1 and it jumps me to A3. Cheers. Anna Frodesiak (talk) 20:19, 8 April 2017 (UTC)

There are many different spreadsheet programs, which all work differently, so there's no one answer that will be correct for all possible spreadsheet programs. If you're using Excel, take a look at this link: [1]. If you're using a different spreadsheet, you need to specify which one you're using. CodeTalker (talk) 20:59, 8 April 2017 (UTC)

Hi CodeTalker. A thousand pardons. I am using OpenOffice. And holy moly, the stackoverflow link you provided is way beyond my ability to understand. I thought there might just be a command or something. Best, Anna Frodesiak (talk) 21:12, 8 April 2017 (UTC)

Wouldn't that behavior look like a bug to anyone who doesn't know that A1=A3 ? StuRat (talk) 23:10, 8 April 2017 (UTC)

Well, StuRat, good point. Actually, it is just for me. I have a list at the beginning of the sheet. Each cell contains =BA1 then the next cell down contains =CA1 then =DA1 then =EA1, etc. BA1 is the text heading of a table there. So, the display at the beginning of the sheet is a sort of index or table of contents of what all the tables are. I would like to be able to click one of those at the beginning of the sheet and magically get taken to that particular table. Anna Frodesiak (talk) 23:54, 8 April 2017 (UTC)

It seems what you need is a Table of contents, but Calc spreadsheets for some reason can't have a TOC like Writer documents. You can use Outlines (Data->Group and outline->Group) to selectively conceal sets of rows or columns. You'll get a vertical or horizontal bar with tiny + and - buttons on it that you can use to expand that part of the table. This is similar to folding.

that said, it is possible to do what you describe by having a macro that sets the focus to a particular cell. However, the macro would have to be assigned to something like a hyperlink or a button - clicking on a cell alone can't invoke a macro (without contortions...) This seems to work:

Sub gotoCell

sheet = ThisComponent.Sheets(0)

targ = Sheet.getCellByPosition(0,2).string 'A3

ThisComponent.CurrentController.select(Sheet.getCellRangeByName(targ))

End sub

This transfers you to the cell whose coordinates are in cell A3. you'd have to manually insert this into the spreadsheet (Tools->Macros->Organize macros->LibreOffice Basic), then draw a button (View->Toolbars->Form controls), then set the button's "Execute action" event (right click->Form controls->Events) to "gotoCell".

I played with OO once. It's completely over-engineered and evil (esp. UNO - the macro above uses only Basic, though) Asmrulz (talk) 15:41, 9 April 2017 (UTC)

Thank you very much, my friend, for taking the time. It is so far beyond my mental pay grade, you wouldn't believe. I must give up on this quest. I must say that it is odd. I am often at a cell that contains something like "=AD37" and would like to jump there to see what is in that cell. These spreadsheets should have a hotkey or something that does that. Thank you again, and best wishes. :) Anna Frodesiak (talk) 22:40, 9 April 2017 (UTC)