Excel - Semi Log Plot
Excel - Semi Log Plot
(OP)
I am having some difficulty plotting permeability and porosity data in excel to find the slope and intercept as a common not a natural log. Where do I find the equation for this common log? Log(k) = b + mǿ. How do I plot a trendline for a common log? The slope should be in the form %¯¹ (1/percent). The data is given below.
Porosity (%) Permeability (mD)
2 0.13
4.1 0.87
4.2 0.6
4.9 0.23
5.2 0.17
6 0.44
6 0.27
6 0.3
6.1 0.5
6.1 0.77
6.5 0.8
6.7 2.01
7.3 3.05
7.7 1.11
7.8 1.47
8.3 0.8
9.2 3.62
9.5 2.71
10 4.55
11.1 15.2
11.7 11.19
12.5 11.08
13.4 77.09
13.9 14.67
14.3 21.1
15 80.44
15.3 61.52
15.7 58.2
15.9 38.88
16.3 157.26
16.5 64.73
16.8 223.71
17.2 96.75
17.5 230.07
17.8 567.03
18.3 117.04
18.8 141.93
20.1 174.85
21.2 233.48
21.7 3209.84
21.9 526.18
Porosity (%) Permeability (mD)
2 0.13
4.1 0.87
4.2 0.6
4.9 0.23
5.2 0.17
6 0.44
6 0.27
6 0.3
6.1 0.5
6.1 0.77
6.5 0.8
6.7 2.01
7.3 3.05
7.7 1.11
7.8 1.47
8.3 0.8
9.2 3.62
9.5 2.71
10 4.55
11.1 15.2
11.7 11.19
12.5 11.08
13.4 77.09
13.9 14.67
14.3 21.1
15 80.44
15.3 61.52
15.7 58.2
15.9 38.88
16.3 157.26
16.5 64.73
16.8 223.71
17.2 96.75
17.5 230.07
17.8 567.03
18.3 117.04
18.8 141.93
20.1 174.85
21.2 233.48
21.7 3209.84
21.9 526.18






RE: Excel - Semi Log Plot
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Excel - Semi Log Plot
exp(ln(x) = 10^log(x) = exp(ln(10)^log(x) = exp(ln(10)*log(x))
--> ln(x) = ln(10)*log(x)
--> log(x) = ln(x)/ln(10)
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: Excel - Semi Log Plot
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Excel - Semi Log Plot
=LOG(x,10)
and
=LOG10(x)
will all return the same number (log x to the base 10)
I don't see why allowing the base to be entered as the second argument is practically useless.
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/
RE: Excel - Semi Log Plot
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Excel - Semi Log Plot
Cheers,
Joerd
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Excel - Semi Log Plot
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.