How do I calculate the log of a number? Don't tell me to use log in
cmath; I'm trying to learn complex math in C++. Got any tips/ideas on
how to do this? Thanks for the help!!!
21  8603 
Go read a math book about how to calculate logarithms by hand. Than go
implement that in code.
"Protoman" writes: How do I calculate the log of a number? Don't tell me to use log in
cmath; I'm trying to learn complex math in C++. Got any tips/ideas on
how to do this? Thanks for the help!!!
You could do it as the way shown here: http://www.convertit.com/go/converti...es=150&Page=65
That's an ebook I have to purchase; I'd like a link to a place that's
free.
Protoman wrote: That's an ebook I have to purchase; I'd like a link to a place that's
free.
The library?
john
I don't go there that often; it's so far away. I'd a like to another
site show how to do it, step by step, by hand, then I'll code it.
Protoman wrote: I don't go there that often; it's so far away. I'd a like to another
site show how to do it, step by step, by hand, then I'll code it.
Fourtunately I have a vast library at my disposal.
log(z) = log|z| + i*phase(z)
phase(z) = atan2(imag(z), real(z))
There is actually some choice about how you calculate this sort of
thing, stuff to do with branch cuts etc. So the above isn't the only way
to do it. Nor should you read any mathematical expertise into my answer.
I'm just quoting from a book.
john
"Protoman" <Pr**********@g mail.com> wrote in message
news:11******** **************@ g44g2000cwa.goo glegroups.com.. . How do I calculate the log of a number? Don't tell me to use log in
cmath; I'm trying to learn complex math in C++. Got any tips/ideas on
how to do this? Thanks for the help!!!
Normalize number into range 1<=x<2 by dividing/multiplying
by 2 repeatedly. Count how many times and call it exponent
(make it negative if normalization required dividing).
Next, repeatedly square the normalized number. Each time the
result >= 2 divide it by 2 and generate "1"; otherwise leave the
result as it is and generate "0". The generated stream of bits are
the fractional part of the exponent in base-2.
Then, the original number == 2^[exponent.fracti on] . Multiply
by a suitable constant to get bases other than 2.
- Risto -
Can you make that just a little clearer?
John Harrison wrote: Protoman wrote:
I don't go there that often; it's so far away. I'd a like to another
site show how to do it, step by step, by hand, then I'll code it.
Fourtunately I have a vast library at my disposal.
log(z) = log|z| + i*phase(z)
phase(z) = atan2(imag(z), real(z))
Hmm, I misread your post, I thought you wanted to calculate the log of a
complex number.
Risto's answer sounded promising, and seemed pretty clear to me. Why not
try coding it and see how far you get.
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