logarithmically spaced vector in a certain range

How to create a logarithmically spaced vector say from values 3 to 10? Thank you!

Answer 1

[Azzi Abdelmalek]

pas=0.1
t=log(3):pas:log(10)
out=exp(t)

%or

n=10 % number of samples
out=exp(linspace(log(3),log(10),n))

[Nuchto]

Thanks, but isn't this an exponential curve?

[Azzi Abdelmalek]

What do you mean?

[Nuchto]

In other words, how would you then create an exponentially spaced vector? Thanks in advance.

[Azzi Abdelmalek]

n=10 % number of samples
out=log(linspace(exp(3),exp(10),n))

[Nuchto]

Thank you!

Answer 2

[Nathan Porter]

Like Marco, I would suggest using logspace. For example,

logspace(1,3,10)

creates a vector of 10 logarithmically spaced values between 10^1 and 10^3. If you instead want the bounds to be determined by a value and not the exponent, I generally use the following:

logspace(log10(3),log10(10),10)

This will create a vector of 10 logarithmically spaced values between 3 and 10.

[Johann Martinez]

Thank Nathan, but what if I have a, b values equals to 0, 0.97, for example?

I mean, the logspaced vector is full of NaN, because of the negative logarithm...

thanks in advance

Answer 3

[Marco]

To my knwoledge you could just use the built-in command logspace.