(Msg. 1) Posted: Thu Apr 19, 2007 2:01 am
Post subject: Adding a manually controlled Line to XY scatter Archived from groups: microsoft>public>excel>charting (more info?)

When plotted you can see that the curve starts off concave and
then changes to convex. The concave section has to be adjusted
out by a process called zero correction. This is done by drawing
a line tangential to the steepest part of the curve and projecting
it down to the X-axis. In this example the line crosses the X-axis
at 0.5, so 0.5 will become the new origin point and the X-axis values
will continue on from there. Zero corrections can be from 0.0 to a
maximum of 0.5, anything over is accepted as 0.5.
At present I just draw a line over the graph, manoeuvre it into place
with the handles and read off the visual result and input it into the
spreadsheet. Not all plots are as neat as this one so it is a judgement
call as to where the line should be placed.
What I would like to do is be able to put the line in place adjusting
the slope and horizontal alignment with the arrows on the keyboard
and have a cell calculating the X-value where Y=0.

Is this possible?.
P.S. For anyone who knows Soils Technology what I have described
is a CBR plot.

(Msg. 2) Posted: Thu Apr 19, 2007 4:34 am
Post subject: Re: Adding a manually controlled Line to XY scatter [Login to view extended thread Info.] Archived from groups: per prev. post (more info?)

I am not quite sure what happens when you enter the new x value into the
worksheet but I imagine one of the following, or some combination of two
or maybe all three, should be useful:

In article , mtmw@hotmail.invalid
says...
> Hi Group,
>
> Given an XY scatter plot with the following data;
>
> X-Values
> Penetration(mm)
> 0.0
> 0.5
> 1.0
> 1.5
> 2.0
> 2.5
> 3.0
> 3.5
> 4.0
> 4.5
> 5.0
> 5.5
> 6.0
> 6.5
> 7.0
> 7.5
>
> Y-Values
> Force(newtons)
> 45
> 620
> 2941
> 5709
> 7960
> 9907
> 11626
> 13177
> 14394
> 15523
> 16595
> 17474
> 18399
> 19242
> 20021
> 20770
>
> When plotted you can see that the curve starts off concave and
> then changes to convex. The concave section has to be adjusted
> out by a process called zero correction. This is done by drawing
> a line tangential to the steepest part of the curve and projecting
> it down to the X-axis. In this example the line crosses the X-axis
> at 0.5, so 0.5 will become the new origin point and the X-axis values
> will continue on from there. Zero corrections can be from 0.0 to a
> maximum of 0.5, anything over is accepted as 0.5.
> At present I just draw a line over the graph, manoeuvre it into place
> with the handles and read off the visual result and input it into the
> spreadsheet. Not all plots are as neat as this one so it is a judgement
> call as to where the line should be placed.
> What I would like to do is be able to put the line in place adjusting
> the slope and horizontal alignment with the arrows on the keyboard
> and have a cell calculating the X-value where Y=0.
>
> Is this possible?.
> P.S. For anyone who knows Soils Technology what I have described
> is a CBR plot.
>
> Sincerely
> Martin
>
>
>

(Msg. 3) Posted: Thu Apr 19, 2007 2:02 pm
Post subject: Re: Adding a manually controlled Line to XY scatter [Login to view extended thread Info.] Archived from groups: per prev. post (more info?)

Thank you Tushar,

Your links helped me to see that I can input the line as a second
series and I can manipulate that through the source data to solve
part of the problem, however, I would still like to manipulate
the line with the arrow keys. We have a very old DOS based
program that does this part of the procedure very well, unfortunately
that is about the only thing that it does do well, the rest is frustratingly
painful.

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