Hi,

I am wondering a bit about the the behaviour of logspace:

Definition: numpy.logspace(start, stop, num=50, endpoint=True, base=10.0)

Reading this I would assume that numpy.logspace(10**-12, 0.0, 100) gives 100 values, from start=10**-12 to stop=0.0, equispaced on a logarithmic scale. But this is not the case. Instead one has to do: numpy.logspace(-12, 0.0, 100)

Docstring: Evenly spaced numbers on a logarithmic scale.

Computes int(num) evenly spaced exponents from start to stop. If endpoint=True, then last exponent is stop. Returns base**exponents.

My impression is that only the very last line is clearly saying what logspace does. And of course the code itself:

y = linspace(start,stop,num=num,endpoint=endpoint) return _nx.power(base,y)

Possible solutions (see below): a) modify logspace so that numpy.logspace(10**-12, 0.0, 100) works b) keep the current behaviour and improve the doc-string

I would be interested in opinions on this.

Best, Arnd

Possible solution for (a) (no error checking yet):

def logspace_modified(start, stop, num=50, endpoint=True): """Evenly spaced numbers on a logarithmic scale.

Computes `num` evenly spaced numbers on a logarithmic scale from `start` to `stop`. If endpoint=True, then last exponent is `stop`. """ lstart = log(start) lstop = log(stop) y = linspace(lstart, lstop, num=num, endpoint=endpoint) return exp(y)

Possible improvent of the doc-string (b) - due to Lars Bittrich:

def logspace(start,stop,num=50,endpoint=True,base=10.0): """Evenly spaced numbers on a logarithmic scale.

Return 'int(num)' evenly spaced samples on a logarithmic scale from 'base'**'start' to 'base'**'stop'. If 'endpoint' is True, the last sample is 'base'**'stop'."""