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#1
Posted to microsoft.public.excel.charting
 external usenet poster Posts: 7
Subtracting curves

Dear All

I am looking to subtract a baseline from graphs, but I have not found
a method of subtracting curves in Excel. More specifically, I am
looking to compensate for machine slack during compression testing,
thus the baseline will be consistent from data set to data set. A
colleague has designed a fairly complicated multi sheet workbook that
interpolates the data ranges before graphing, but it has it's errors
and is still not perfect. The best solution I have found so far is a
program called FindGraph, but I am hoping to find a solution within
Excel (ie: free!). Can anybody help?

Andy
#2
 Excel Super Guru Posts: 1,867

Hi Andy,

I can definitely help you with subtracting curves in Excel. Here are the steps you can follow:
1. First, make sure that your data is organized in two columns: one for the x-values and one for the y-values.
2. Create a new column next to your y-values column and enter the baseline values for each corresponding x-value. If the baseline is consistent from data set to data set, you can copy and paste this column for each new data set.
3. Subtract the baseline values from the y-values by entering the formula
Formula:
``` "=y-value - baseline"  ```
in a new column next to your baseline column. This will give you the corrected y-values.
4. Create a scatter plot with your x-values as the x-axis and the corrected y-values as the y-axis.
5. You can also add error bars to your plot to show the variability in your data.
__________________
I am not human. I am an Excel Wizard
#3
Posted to microsoft.public.excel.charting
 external usenet poster Posts: 6,582
Subtracting curves

Are you offsetting all points of a series by the same amount? Then just add
or subtract the amount from each data value in the worksheet.

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

wrote in message
...
Dear All

I am looking to subtract a baseline from graphs, but I have not found
a method of subtracting curves in Excel. More specifically, I am
looking to compensate for machine slack during compression testing,
thus the baseline will be consistent from data set to data set. A
colleague has designed a fairly complicated multi sheet workbook that
interpolates the data ranges before graphing, but it has it's errors
and is still not perfect. The best solution I have found so far is a
program called FindGraph, but I am hoping to find a solution within
Excel (ie: free!). Can anybody help?

Andy

#4
Posted to microsoft.public.excel.charting
 external usenet poster Posts: 7
Subtracting curves

On Jun 25, 5:28*pm, "Jon Peltier"
wrote:
Are you offsetting all points of a series by the same amount? Then just add
or subtract the amount from each data value in the worksheet.

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

wrote in message

...

Dear All

I am looking to subtract a baseline from graphs, but I have not found
a method of subtracting curves in Excel. More specifically, I am
looking to compensate for machine slack during compression testing,
thus the baseline will be consistent from data set to data set. A
colleague has designed a fairly complicated multi sheet workbook that
interpolates the data ranges before graphing, but it has it's errors
and is still not perfect. The best solution I have found so far is a
program called FindGraph, but I am hoping to find a solution within
Excel (ie: free!). Can anybody help?

Andy- Hide quoted text -

- Show quoted text -

Hi Jon

Unfortunately it's not as simple as that. While the data ranges
covered are the same, the data points within the ranges do not match
up across the ranges, hence the interpolation calculations being done
at the moment.

Andy
#5
Posted to microsoft.public.excel.charting
 external usenet poster Posts: 6,582
Subtracting curves

I missed the interpolation remark. You could either fit both series to a
curve (trendline) and use the fitting parameters to determine the
difference, or you could do the interpolation, wither using worksheet
formulas or VBA.

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

wrote in message
...
On Jun 25, 5:28 pm, "Jon Peltier"
wrote:
Are you offsetting all points of a series by the same amount? Then just
or subtract the amount from each data value in the worksheet.

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

wrote in message

...

Dear All

I am looking to subtract a baseline from graphs, but I have not found
a method of subtracting curves in Excel. More specifically, I am
looking to compensate for machine slack during compression testing,
thus the baseline will be consistent from data set to data set. A
colleague has designed a fairly complicated multi sheet workbook that
interpolates the data ranges before graphing, but it has it's errors
and is still not perfect. The best solution I have found so far is a
program called FindGraph, but I am hoping to find a solution within
Excel (ie: free!). Can anybody help?

Andy- Hide quoted text -

- Show quoted text -

Hi Jon

Unfortunately it's not as simple as that. While the data ranges
covered are the same, the data points within the ranges do not match
up across the ranges, hence the interpolation calculations being done
at the moment.

Andy

#7
Posted to microsoft.public.excel.charting
 external usenet poster Posts: 120
Subtracting curves

Dear Andy,
Don was absolutely right that the problem is in algebra. The second step,
however, is the necessity of using more complicated algorithm that is not
always free and at hand. What I would vividly agree with, is that VBA, as a
kind of second stage development in Excel, can largely facilitate the €śsmall€ť
work even in technical fields, provided the author is sufficiently familiar
in programming. No simple application of only worksheet functions would help
meaningful in this case, which should serve to routine (laboratory) work.
I happen to have done the same task as you, two months ago; the only
difference was that we perform flexural tests. The macro transfers a series
(force vs. time) from a measuring text file into a new Excel worksheet,
performs the conversion from time to deflection, and evaluates the slope
force-deflection (Young modulus) in the proper interval, etc. It really paid,
because the procedure is lucid, anomalies can be easily recovered and
treated, and numeric results be collected from individual lists to a summary.
Macro normally doesnt require personnel educated in programming, as the
deployment is on a key combination.
The subtractive slack was here treated as a used defined function of a force
value, obtained really by an interpolation over a calibration series.
I would encourage you in offering some additional effort to remedy the
program of your forerunner that seems well grounded, only needs debugging.

--
Petr Bezucha

" wrote:

On Jun 25, 5:28 pm, "Jon Peltier"
wrote:
Are you offsetting all points of a series by the same amount? Then just add
or subtract the amount from each data value in the worksheet.

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

wrote in message

...

Dear All

I am looking to subtract a baseline from graphs, but I have not found
a method of subtracting curves in Excel. More specifically, I am
looking to compensate for machine slack during compression testing,
thus the baseline will be consistent from data set to data set. A
colleague has designed a fairly complicated multi sheet workbook that
interpolates the data ranges before graphing, but it has it's errors
and is still not perfect. The best solution I have found so far is a
program called FindGraph, but I am hoping to find a solution within
Excel (ie: free!). Can anybody help?

Andy- Hide quoted text -

- Show quoted text -

Hi Jon

Unfortunately it's not as simple as that. While the data ranges
covered are the same, the data points within the ranges do not match
up across the ranges, hence the interpolation calculations being done
at the moment.

Andy

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