I tried it in XL 2000, XP, and 2003 with the following results:

1) The lines are not coincident, but series1 is also not right.
Corresponding to y=0.1, you should see x=(0.1-K1)/S1=0.02475. The
placement varies slightly among versions, but is in the vicinity of 0.035

2) Your results are reproduced in all three versions.

I had previously observed that zooming in on the scale with smoothed
lines could produce very inaccurate curves between points, but had not
known that the problem also plagued straight connecting lines.

Jerry

Philip_plf wrote:

Try plotting two lines in a XY-chart:
Each line should consist of 2 (X,Y) points. The X values of both lines
should be set 0 and 5. The Y values should be calculated from other cells as:
Y=S1*X+K1 and Y=S2*X+K2. Where S1 and S2 are the slopes and K1 and K2 are
the interceptions. Set S1=1, S2=2, K1=0.001 and K2=0.001. Plot the lines in a
XY-Chart. The next step is important: Set the X-Axes scaled from 0 to 0.1 and
the Y-axes scaled from 0 to 0.1.

The BUG:
Now try changing S1 to S1=4. It is clear that something is wrong.The lines
should have different slope but they have the same!!
Go back, set S1=1. Try to chage the X value of 5 to something else, eg.
100.. whoaa.. strange result. There should have been no change in the chart,
but suddently the chart shows a plot, where both slopes are same but not
equal to what S1 and S2 where in the beginning!


Can anyone help me to sort out the problem? I where trying to plot something
with a small zoom on, but the result where WRONG!
Is this a real bug? Does anyone get the same error?

I've left an example on the net:
http://home.tiscali.dk/phreaky/excel....chart.bug.xls