Lines of a particular slope that can be moved around

[routeram]

Hello to all,

I am plotting a graph that can be approximated using 2 straight line
(follows one straight line in a particular range and the other line i
the remaining range). The slope of the 2 lines (approximating th
plotted curve) can be calculated using formulae.

Right now I have 2 lines from the drawing toolbar on the chart - s
that the user can move the line on the graph and see that it is indee
made of 2 straight lines. In this case, the line remains static and th
user has to change the slope of the line each time parameters change. I
there anyway to draw a line of specified variable slope that can b
moved around?

I hope I made myself clear. Would be glad to clarify any ambiguities.

Please help. Thanks.

Regards,
Ra

 

[Bernard Liengme]

I do exactly that in one of my applications (finding critical micelle conc)
but it would take too long to explain in general. Send me the data (to my
private email) and I will make you return it in working order.
Do you need to know (a) the two slopes and (b) the point of intersection?

 

[Jon Peltier]

I know Bernard is helping you offline, but I thought I'd describe an approach. I would construct
two 2-point series on the chart, which link to values calculated according to cells that hold
slope and intercept values. I'd let the user either type in custom values, or use a slider or
buttons to change these values. As the values changed, the lines would move and skew around.

A more detailed approach might be to actually indicate a subset of the charted points, and
create a trendline from them. I've done this using chart events to select points, then creating
a new series with only the selected points, and dropping in the trendlines.

- Jon
-------
Jon Peltier, Microsoft Excel MVP
Peltier Technical Services
Tutorials and Custom Solutions
http://PeltierTech.com/
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