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ttokoro
ttokoroAnswer
21-Topaz I
Apr 19, 2023 11:22 PM UTC

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t.t.
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ttokoro
ttokoro21-Topaz IAnswer
21-Topaz I
Apr 19, 2023 11:22 PM UTC

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t.t.
terryhendicott
terryhendicott21-Topaz II
21-Topaz II
Apr 19, 2023 11:34 PM UTC


Hi,

Here is the pwrfit() to the data.

Capture.JPG

Cheers

Terry

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HA_106612323-NewcomerAuthor
3-Newcomer
Apr 19, 2023 11:52 PM UTC

thank you Mr.Terryhendicott you are so kind

 

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Werner_E
Werner_E25-Diamond I
25-Diamond I
Apr 20, 2023 1:38 AM UTC

You may use "submatrix" to get only parts of your vectors and use "slope" on them.

The two slopes you seem to be looking for are

Werner_E_0-1681954574225.png

 

You may also use "line" to get slope and intersect for the linear regression in one go and use them to draw the line fit

Werner_E_1-1681954669477.png

 

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HA_106612323-NewcomerAuthor
3-Newcomer
Apr 20, 2023 12:35 PM UTC

thanks, Mr. Werner that's so helpful. But the reason I exclude some values from the vector is that I can't conduct log(0), I tried to do a program in Mathcad to fulfill this but I couldn't make it, can you please help me out to do this issue in a program that calculates the slope of between the log of the data with excluding any value that equals to zero 

 

with regards

 

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Werner_E
Werner_E25-Diamond I
25-Diamond I
Apr 20, 2023 1:23 PM UTC

Here is a way to eliminate all values in a vector which are zero or negative:

Werner_E_0-1681996657420.png

 

The method will fail if no values of zero or below are in the vector because match will fail in that case.
You can deal with this problem by using "try ... on error..."

Werner_E_1-1681996941106.png

One drawback still remains - if all values are zero or negative, this routine returns the vector unchanged instead of returning an error or Nan or the like. Don't think this would be an issue in your application, though.

 

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