Partially answer!

Well, at least a better diagnosis:

Turns out that the symptom noted (dashed lines on trendlines print as
continuous lines) only occurs for curved trendlines (such as polynomial),
not linear.

It appears that what's happening is this:

Excel is indeed using the dashed line format, applying it to the dashed
lines between the points that it's calculating for the trendline.

But the higher the resolution of the picture (eg: printing, or zooming in)
the more finely does Excel calculate the points, And hence the shorter those
line segments... to the point where the the length between the points is
less than the length of even one dash.

Hence the appearance of a continuous line, albeit a bit messy in some views
as the adjacent initial dash segments somewhat jumble together.

OK, so this could be relieved if one could set the interval at which Excel
calculates the curve, but I don's see such a setting in the UI or a property
in the object model.

Alternatively, with some programming, if one had access to the trendline's
data series, one could set a pattern of alternating line-segment colors (or
say 3 white, 3 black, 3 white... if they are very fine). But I don't see a
way to get at the trendline's series either.

Any other ideas?

Graham
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Graham Wideman
Microsoft Visio MVP
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"Graham Wideman" wrote in message
...

Folks:

Bug? Known issue? Or Operator Error?

I notice that in an Excel Chart, if you set the line format of a trendline
to one of the dashed formats it has an oddly coarse appearance when viewed
in the worksheet window (dashed but messy), any when printed (or viewed in
Print View) the line style appears as continuous.

The same dashed line formats for regular data series view and print just
fine.

We've tried this on Excel 2002 and 3, on two different PCs with two
entirely different sets of data and excel docs and printing to three
different brands of printers.

Not sure if printer driver has any impact on any of this, but the fact
that regular series print fine probably eliminates that.

Any clues? Confirmation that you too see this? Thanks,

Graham