PCDmanager Surface Tension Data Fitting

[nrgeng]

In attempting to plot surface tension data, whenever the [Fit] button is selected, the plot y-axis range reverts to 0.07 to 0.13 units despite the imported data being in the range of 0.02 to 0.05 units. The right-mouse-button menu can be used to change the y-axis range to 0.02 to 0.05 units. When this is done, the imported data show as points on the plot and all looks good until the [Fit] button is selected wherein the imported data jumps out of the plotted area.

The selected Equation plots with a positive slope. Unfortunately a line through the imported data points indicates a negative slope. The slope of the plotted Equation line does not change to a negative value to fit the imported data. R2 displays as zero.

No amount of clearing data, resetting, changing Equations, or anything else changes the bottom line, which is a lot of effort for nothing accomplished. Please provide any information that can solve these frustrating problems. Thanks.

[jasper]

Harry will be back in his office 3 weeks from now. He will get back to you then.

[hkooijman]

Can you provide the data you were trying to fit as well as the equation type/number you were using? I understand that the initialization of the fitting process needs improvment but this is a non-trivial task.

Note that the fit is not a least square fit, but a http://en.wikipedia.org/wiki/Levenberg% ... _algorithm type. As such you will encounter differences with other sources.

Note that doing a fit always resets the graph settings, as this may be needed to visualize the new plot. I can only prevent this from happening if I would make a checkbox to keep the settings during the fit, however, typically this is not what most users would want to happen, or?

[nrgeng]

I am using PCDmanager v6.96 (2100/6)

I have emailed the file "Compound W surface tension (K, N%m) 1.1."

Surface Tension Data Fitting
Problem: No Plot for Eqn 106

Seems to be a different problem from before. The number of <Table> points seems to read in the 3 data pairs (after the 2nd attempt).

Please continue to work on PCDmanager.

[hkooijman]

The blank screen for the plot should now not appear anymore.
Further note that the fit capability will be improved in v7.00
Harry