The slope of a graph

[svabbi@my-deja.com]

I'm trying to calculate the slope of a graph aquired by a daq device.
I have to find the part of the curve where it reaches the peak, not the
maximum. Can anybody point out a vi or function to find an
approximation to the peak?

Best Regards
Svavar Von Eisland


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Share what you know. Learn what you don't.

[James Olive]

I think you'll need the Full Development System flavor of LabVIEW in order
to load this example, but there's a very nice Peak Detection example that
ships with the product. Go to Help>>Search Examples and click on "Signal
Processing," then "Peak Detection."

--John Lum

svabbi@my-deja.com wrote:

> I'm trying to calculate the slope of a graph aquired by a daq device.
> I have to find the part of the curve where it reaches the peak, not the
> maximum. Can anybody point out a vi or function to find an
> approximation to the peak?
>
> Best Regards
> Svavar Von Eisland
>
> Sent via Deja.com http://www.deja.com/
> Share what you know. Learn what you don't.

[James Olive]

I think you'll need the Full Development System flavor of LabVIEW in order
to load this example, but there's a very nice Peak Detection example that
ships with the product. Go to Help>>Search Examples and click on "Signal
Processing," then "Peak Detection."

--John Lum

svabbi@my-deja.com wrote:

> I'm trying to calculate the slope of a graph aquired by a daq device.
> I have to find the part of the curve where it reaches the peak, not the
> maximum. Can anybody point out a vi or function to find an
> approximation to the peak?
>
> Best Regards
> Svavar Von Eisland
>
> Sent via Deja.com http://www.deja.com/
> Share what you know. Learn what you don't.

[James Olive]

I think you'll need the Full Development System flavor of LabVIEW in order
to load this example, but there's a very nice Peak Detection example that
ships with the product. Go to Help>>Search Examples and click on "Signal
Processing," then "Peak Detection."

--John Lum

svabbi@my-deja.com wrote:

> I'm trying to calculate the slope of a graph aquired by a daq device.
> I have to find the part of the curve where it reaches the peak, not the
> maximum. Can anybody point out a vi or function to find an
> approximation to the peak?
>
> Best Regards
> Svavar Von Eisland
>
> Sent via Deja.com http://www.deja.com/
> Share what you know. Learn what you don't.

[B & C Duffey]

You need to incrementally measure the slope from point to point and keep
track of where the slope goes to zero (or a really small number) this could
be at several points depending on how many minimums and maximums there are,
to tell if it is a max or a min you will need to keep track of the sign
changes on either side of the zero slope point(s) (derivitive). Also
depending on how noisy your data is you may need to smooth it as you go -
maybe some type of running average. The end points of your data will have
to be excluded since the slope is undefined (ie you can't take a slope of a
single point).

Refer to your differential equations / calculaus book for futher info. 🙂

Chris


svabbi@my-deja.com wrote in message <7o926e$3bo$1@nnrp1.deja.com>...
>I'm trying to
calculate the slope of a graph aquired by a daq device.
>I have to find the part of the curve where it reaches the peak, not the
>maximum. Can anybody point out a vi or function to find an
>approximation to the peak?
>
>Best Regards
>Svavar Von Eisland
>
>
>Sent via Deja.com http://www.deja.com/
>Share what you know. Learn what you don't.