Calculate the Natural logarithm ln

I'm trying to calculate the natural log of temperature and pressure ratio for an ideal gas in order to find the entropy change.

I've read some articles that says it's the same thing as log(x), but that doesn't make any sense.

I have some literture data to compare with. Using log(x) gives me incorrect values.

Is there a way to use the natural log ln in MATLAB?

[Stephen23]

"I've read some articles that says it's the same thing as log(x), but that doesn't make any sense. "

I have no idea what "articles" you have read, but when I read the log documentation

https://www.mathworks.com/help/matlab/ref/log.html

it clearly states that "log(X) returns the natural logarithm ln(x) of each element in array X."

"Using log(x) gives me incorrect values."

What are the input values, what output values do you expect, and how are you checking them?

[Irma Espinoza]

I have the same problem, I'm trying to get natural logarithm of vector STR1, please see below.The result I get for each of the elements is incorrect, for example, element 1 is 1.00001626396027 , the natural logaritm I get from matlab is 0.016263828016221, the result I get from excel and other methods is 0.0000162638280133342.

for n=1:finish 
STR11(n)=log(STR1(1,n))
end 

[Steven Lord]

Make sure you're using the version of the log function included in MATLAB, not one you've written or obtained elsewhere.

which -all log

Can you show us the output of that command? This should list two built-in functions and (depending on which toolboxes you have installed) a few others all under the toolbox subdirectory of matlabroot.