Questioning the math Re: reluctance

You need another pair of brackets to make the above correct:

Reluctance = (1/(2*pi*t*u))*[ln(r2)-ln(r1)]

= [ln(r2)-ln(r1)]/(2*pi*t*u)

If you recall your math, ln(A) - ln(B) = ln(A/B) right?

Just as e^a * e^b = e^(a+b)

(related to how slide rules work...)

Best regards, Spehro Pefhany

Thanks Spehro, but I'm not on board yet. I agree that,

(1/(2*pi*t*u))*[ln(r2)-ln(r1)] = [ln(r2)-ln(r1)]/(2*pi*t*u)

But, the author then reduces [ln(r2)-ln(r1)]/(2*pi*t*u) to [ln(r2/r1)] / (2*pi*t*u)

When I plug numbers into these two I get different answers. What am I missing? My numbers, ln=2.718, r2=.6, r1=.5, t=.063, u=3500

Oh, and what about,

As above. Thank you, Mike

ln is not a number, it's a function.

In this case, ln(r2/r1) = ln(0.6/0.5) = 0.182

Thanks Greg, Ok, I did it on the calculator and all is well. Almost, I don't know what function I'm doing, I'm printing some info to look over so I can understand it. Thanks again, Mike I still need help as below,

ln(x) is the logarithm of x to the base 2.718281828... It's not a constant, rather it's a (transcendental) function. Any scientific calculator (even the Windows calculator) will allow you to plug the numbers in and calculate it.

Best regards, Spehro Pefhany

Look, Shit For Brains, we don't need idiots like you coming in here with you trans mediocre stuff and explaining number stuff.

Next thing you know someone will think it's a really bad idea to take on someone elses long term debt, at reduced repayments, because some stoopid f*ck up like you broke the news to the government about sums and stuff and they are going to stop bailing the f****rs out!!!!!!

That's OK, you go and piss on everyone elses Christmas.

Bastard

DNA

LOL. For that outburst, your credit cards will have their interest compounded *instantaneously*.

Best regards, Spehro Pefhany

Spehro Pefhany a écrit :

He he, reminds me a teacher renowned for his ignorance that, after some lengthy demonstration, got something like Ln(x+x^2)/Ln(x-x^2) with x approaching 0.

He 'just simplified' by Ln, leaving 1 as a result (which happens to be right in this case).

Looking to Genome's emails, he have bad days everyday... Some people does not have the first 7 years old, they just jumped directly to (i)maturity. Pretty bad. Vasile

Genome suffers(?) from a condition known in the medical literature as coprographia. It does not negatively affect his formidable circuit design abilities. You should be more understanding of people with such issues.

Best regards, Spehro Pefhany