# Need to get slope of peaks on excel graph

C

#### Capillod

I have a graph with many peaks which are decreasing logarithmically and i
need to get the slope of these peaks ignoring the "Noise" which is below
these peaks.

Any suggestions ???

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C

#### capillod

Sorry I probaly didnt word the question well. My graph has many peaks e.g.
20 peaks, each one smaller than the previous one. What i am trying to do is
draw a lins through the top of these peaks and then get the slope of this
line.

I have tried using the trendling but with no success. It does give me ths
slope of the whole graph which is useful but not what i am looking for.
Regards

Capillod

G

#### Guest

capillod wrote:

Sorry I probaly didnt word the question well. My graph has many peaks e.g. 20 peaks, each one smaller than the previous one. What i am trying to do is draw a lins through the top of these peaks and then get the slope of this line. I have tried using the trendling but with no success. It does give me ths slope of the whole graph which is useful but not what i am looking for. Regards Capillod "Capillod" wrote:

I have a graph with many peaks which are decreasing logarithmically and i need to get the slope of these peaks ignoring the "Noise" which is below these peaks. Any suggestions ???

Can you create a helper column which contains only the data points for the peaks.Â  Then plot that on your chart also (in some invisible color if you wish) and put a trend line through them, rather than through all your data points.

For a one time use you can probably manually copy over a few relevant peak data points easiest.Â  If this is some repeated process you want to automate then you should be able to automatically copy over only the points immediately following a change in sign of the slope or some such.

Good luck....

Bill

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G

#### Gary's Student

You have what looks like a decaying harmonic process. Something like
amplitude versus time.. Assume that times are in A1 through A1000. Assume
that amplitudes are in B1 through B1000. In column C2 enter =B2-B1 and copy
the formula down. Column C will show if you are ascending or descending.

In Column D3 enter =IF(AND(C3<0,C2>0),1,0)
Column D will have zeros everywhere except just after the peaks it will have
ones.

Use Tools -> Filter to see only the peaks. Plot this and measure the slope.

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