Re[2]: Recalculate and Recalculate Hard in Calc

Mike,

Many thanks for clarifying that. It helps me to understand what is going 
on.

Regards,

Steve


------ Original Message ------
From: "Mike Kaganski" <mikekaganski@hotmail.com>
To: "Steve Fanning" <stevemfanning.wh@gmail.com>; 
"libreoffice@lists.freedesktop.org" <libreoffice@lists.freedesktop.org>
Sent: 09/06/2020 07:53:47
Subject: Re:  Recalculate and Recalculate Hard in Calc

> Hi,
>
> On 08.06.2020 13:01, Steve Fanning wrote:
> >  I’m having a problem understanding the Help information for these
> >  functions (search for “recalculate” in the Help index).
> >
> >  The Help seems to state that choosing Data > Calculate > Recalculate (or
> >  its equivalent shortcut F9) “recalculates the currently selected cells
> >  and formula cells that depend on them”. Whatever I try in Calc, these
> >  interactions affect lots of cells, not just those currently selected.
> >
> >  In an empty spreadsheet, try the following:
> >  (a) Set Data > Calculate > AutoCalculate to off.
> >  (b) Type =a1+1 into cell a2.
> >  (c) Type the value 1 into cell a1.
> >  (d) Type =e5+1 into cell e6.
> >  (e) Type the value 1 into cell e5.
> >  (f) Select cells e5 and e6.
> >  (g) Choose Data > Calculate > Recalculate or press F9.
> >  When I do this, the value in the unselected cell a2 is updated.
> >
> >  Is the Help inaccurate or am I muddled?
> >
> >  And, if my example above is valid, what does Recalculate Hard do that
> >  Recalculate doesn’t?
>
> FTR: the code for Recalculate (F9) is ScDocShell::DoRecalc; for
> Recalculate Hard (Ctrl+Shift+F9) is ScDocShell::DoHardRecalc.
>
> The former first sets current cell "dirty", then calls
> ScDocument::CalcFormulaTree (that recalcs *all* *dirty* cells in the
> document) and ScDBFunc::UpdateCharts (to make sure the changes get into
> charts).
>
> Thus, if the document contains many dirty cells (as working in disabled
> AutoCalculate mode), F9 would make sure that currently selected cell is
> dirty (to make sure it recalcs), but then will recalc not only it, but
> all other dirty cells. But called next time in the same mode, only
> current cell plus cells made dirty after last recalc will update (not
> all formulas, which might be many thousands).
>
> ScDocShell::DoHardRecalc calls ScDocument::CalcAll (that recalcs *all*
> formula cells, not only dirty ones), then ScDocFunc::DetectiveRefresh,
> then ScDBFunc::UpdateCharts.
>
> Thus Ctrl+Shift+F9 will take much longer than F9 in documents where most
> cells are up-to-date.
>
> HTH.
>
> --
> Best regards,
> Mike Kaganski