Re: Graphing points to the 10^-19
- From: Lala <Lala@xxxxxxxxxxxxxxxxxxxxxxxxx>
- Date: Sat, 12 May 2007 13:36:02 -0700
Yes thank you, it is a software issue. I thought I was doing something wrong
/ human error in inputing data or formatting the graph.
I hope this bug gets fixed because I'd rather not get another version of
excel and I might need to graph data with numbers this small again.
Anyway to get automatically notified should a patch for this bug gets issued?
Thanks for all the responses/help.
"Jon Peltier" wrote:
Without doing anything special, I created a chart and added a trendline. It.
worked as expected, and I got this formula:
y = -2.3507E-18x + 5.4943E-19
R2 = 9.9921E-01
This worked the same in Excel 2000 and in 2003. Then I tried it in Excel
2007 and it failed in the same manner that you described. The Y axis only
showed 0.0000E00 at the bottom, and no more values, and the formula showed Y
= 5.4943E-19, omitting the constant. Excel apparently thought this was a
rounding error and coerced it to zero. I ran a set of trials where I
multiplied the Y values of each trial by ten to get the Y values for the
next. My regression formulas looked like:
y = 5.49429E-19 [R² = 9.99213E-01]
y = 5.49429E-18 [R² = 9.99213E-01]
y = 5.49429E-17 [R² = 9.99213E-01]
y = 5.49429E-16 [R² = 9.99213E-01]
y = -2.35066E-14x [R² = 9.99213E-01]
y = -2.35066E-13x + 5.49429E-14 [R² = 9.99213E-01]
y = -2.35066E-12x + 5.49429E-13 [R² = 9.99213E-01]
y = -2.35066E-11x + 5.49429E-12 [R² = 9.99213E-01]
The first formula came from your example. Note that the constant has the
same pre-exponential factor for all of the formulas (5.49429) except for the
case when it would be 5.49429E-15, which sounds like a threshold for being
considered a rounding error. In all cases where the coefficient of X wasn't
ignored, the coefficient's pre-exponential factor was the same (-2.35066),
and in all cases, R² was the same (0.999213). I repeated this in Excel 2003,
and the formulas were identical except for the exponents of the fitting
constants.
I'd classify this one more as a bug than as a feature.
- Jon
-------
Jon Peltier, Microsoft Excel MVP
Tutorials and Custom Solutions
http://PeltierTech.com
_______
"Lala" <Lala@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:BBBD75D9-D132-47FF-9BBC-2F4E5D98107F@xxxxxxxxxxxxxxxx
Yes the graph choosen is the xy scatter graph. The values I'm trying to
graph
are :
x = 0.1111 y= 2.872*10^-19 ; (2.872E-19 when actually posting in the cell)
x = 0.0625 y= 4.043*10^-19 ; (4.043E-19)
x = 0.0400 y= 4.576*10^-19 ; (4.576E-19)
x = 0.0277 y= 4.814*10^-19 ; (4.814E-19)
Again the Y values of (1E-19 to 6E-19) are not posting, only 0 value is
posting.
When editing the y axis the minimum value on automatic is 0 and the
maximum
does say 6.0E-19. But on the actual agraph I don't see these values. So
when
doing a line graph I only get a linear equation of y=5E-19 instead of
y=mx+b.
Excel does graph the data points and when adding data labels, the values
appear. It's just the division values (1.00E-19 to 6.00E-19) on the y axis
that doesn't appear.
I've also tried setting the cells to scientific numbers, general and
numbers
but that didn't help.
It has to be the program because I've had 2 people graph my data and it
worked on their software.
"Bernard Liengme" wrote:
It would be helpful to see at least 5 data points (both the x and the y
values): could you list them for us?
Are you sure you have made an XY chart and not a Line chart?
If you wish you may send me a file with the data
best wishes
--
Bernard V Liengme
www.stfx.ca/people/bliengme
remove caps from email
"Lala" <Lala@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:972F4E9D-ACB5-4371-BE51-48541F2D5B2B@xxxxxxxxxxxxxxxx
I have the home and student 2007 version. When graphing a scatter graph
with
the Y axis having 10 to the negative power, excel doesn't show the
values
on
the y axis. It only shows the 0 intercept value. I've tried editing the
axis
values but the number still doesn't display and excel automatically
puts
the
number to at least 10 decimal places, ie 5.000000000000001E-19.
When I just click automatic, the right values appear in the edit menu
but
the y values still won't show on the actual graph. So when doing a
trendline
the equation doesn't show an m slope value, ie y=5E-19. A friend
graphed
my
data on an older version excel and it graphed it properly with the
proper
y
values displaying, and linear trendline equation was in right format of
y
=
mx + b, ie y= -2E-18x + 5E-19
Could my software be defective? Or are some features disabled?
- References:
- Re: Graphing points to the 10^-19
- From: Bernard Liengme
- Re: Graphing points to the 10^-19
- From: Jon Peltier
- Re: Graphing points to the 10^-19
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