Interpolation using GROWTH function?
 

Background: I'm a instrument technician trying to use Excel to scale a
nonlinear device which streams a measurement (ultimately, force in
pounds) to a .CSV file. The Data is formatted as a raw, unscaled number
in one column and a adjacent timestamp in another column.

If the sensor was linear I could simply multiply that raw number by the
appropriate scaling factor to get pounds but this particular sensor is
not.

If I take sample readings with known standard weights at regular
intervals alongs the device's full scale and plot Pounds (x) and the
device output (Y) can I use the GROWTH function to create a formula
which will then automatically condition/scale/interpolate the devices
output in my spreadsheet chart when I'm using it out in the field?

I know GROWTH can plot points in the future but can it determine points
in between? Is this the right function for this job or would something
else be more appropriate?


--
victurbo
------------------------------------------------------------------------
victurbo's Profile: http://www.excelforum.com/member.php...o&userid=27162
View this thread: http://www.excelforum.com/showthread...hreadid=466735

I am a scientist and this is what I would do:
Make a plot in Excel of Known Pounds (x-axis) against Measured Values
(y-axis)
Add a polynomial trendline (up to 4 powers) to find a good fit, note which
power is used
Use LINEST with that power to get these values into cells (see my website)
Use the LINEST values to compute the Actual Pounds
Contact me a personal email if more details needed
best wishes
--
Bernard V Liengme
www.stfx.ca/people/bliengme
remove caps from email

"victurbo" wrote in
message ...

Background: I'm a instrument technician trying to use Excel to scale a
nonlinear device which streams a measurement (ultimately, force in
pounds) to a .CSV file. The Data is formatted as a raw, unscaled number
in one column and a adjacent timestamp in another column.

If the sensor was linear I could simply multiply that raw number by the
appropriate scaling factor to get pounds but this particular sensor is
not.

If I take sample readings with known standard weights at regular
intervals alongs the device's full scale and plot Pounds (x) and the
device output (Y) can I use the GROWTH function to create a formula
which will then automatically condition/scale/interpolate the devices
output in my spreadsheet chart when I'm using it out in the field?

I know GROWTH can plot points in the future but can it determine points
in between? Is this the right function for this job or would something
else be more appropriate?


--
victurbo
------------------------------------------------------------------------
victurbo's Profile:
http://www.excelforum.com/member.php...o&userid=27162
View this thread: http://www.excelforum.com/showthread...hreadid=466735

Also, check my response to the same request at the mrexcel.com web
site.

--
Regards,

Tushar Mehta
www.tushar-mehta.com
Excel, PowerPoint, and VBA add-ins, tutorials
Custom MS Office productivity solutions

In article ,
says...

Background: I'm a instrument technician trying to use Excel to scale a
nonlinear device which streams a measurement (ultimately, force in
{snip}

Short answer: yes, GROWTH can handle interpolation as well as
extrapolation. GROWTH uses an exponential model [y=A*exp(Bx)] to
correlate the data. If this type of model will represent your data
well, then GROWTH should work fine.


--
MrShorty
------------------------------------------------------------------------
MrShorty's Profile: http://www.excelforum.com/member.php...o&userid=22181
View this thread: http://www.excelforum.com/showthread...hreadid=466735