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+__all__ = ['logspace', 'linspace']
+
+import numeric as _nx
+from numeric import array
+
+def linspace(start, stop, num=50, endpoint=True, retstep=False):
+ """
+ Return evenly spaced numbers over a specified interval.
+
+ Returns `num` evenly spaced samples, calculated over the
+ interval [`start`, `stop` ].
+
+ The endpoint of the interval can optionally be excluded.
+
+ Parameters
+ ----------
+ start : scalar
+ The starting value of the sequence.
+ stop : scalar
+ The end value of the sequence, unless `endpoint` is set to False.
+ In that case, the sequence consists of all but the last of ``num + 1``
+ evenly spaced samples, so that `stop` is excluded. Note that the step
+ size changes when `endpoint` is False.
+ num : int, optional
+ Number of samples to generate. Default is 50.
+ endpoint : bool, optional
+ If True, `stop` is the last sample. Otherwise, it is not included.
+ Default is True.
+ retstep : bool, optional
+ If True, return (`samples`, `step`), where `step` is the spacing
+ between samples.
+
+ Returns
+ -------
+ samples : ndarray
+ There are `num` equally spaced samples in the closed interval
+ ``[start, stop]`` or the half-open interval ``[start, stop)``
+ (depending on whether `endpoint` is True or False).
+ step : float (only if `retstep` is True)
+ Size of spacing between samples.
+
+
+ See Also
+ --------
+ arange : Similiar to `linspace`, but uses a step size (instead of the
+ number of samples).
+ logspace : Samples uniformly distributed in log space.
+
+ Examples
+ --------
+ >>> np.linspace(2.0, 3.0, num=5)
+ array([ 2. , 2.25, 2.5 , 2.75, 3. ])
+ >>> np.linspace(2.0, 3.0, num=5, endpoint=False)
+ array([ 2. , 2.2, 2.4, 2.6, 2.8])
+ >>> np.linspace(2.0, 3.0, num=5, retstep=True)
+ (array([ 2. , 2.25, 2.5 , 2.75, 3. ]), 0.25)
+
+ Graphical illustration:
+
+ >>> import matplotlib.pyplot as plt
+ >>> N = 8
+ >>> y = np.zeros(N)
+ >>> x1 = np.linspace(0, 10, N, endpoint=True)
+ >>> x2 = np.linspace(0, 10, N, endpoint=False)
+ >>> plt.plot(x1, y, 'o')
+ >>> plt.plot(x2, y + 0.5, 'o')
+ >>> plt.ylim([-0.5, 1])
+ >>> plt.show()
+
+ """
+ num = int(num)
+ if num <= 0:
+ return array([], float)
+ if endpoint:
+ if num == 1:
+ return array([float(start)])
+ step = (stop-start)/float((num-1))
+ y = _nx.arange(0, num) * step + start
+ y[-1] = stop
+ else:
+ step = (stop-start)/float(num)
+ y = _nx.arange(0, num) * step + start
+ if retstep:
+ return y, step
+ else:
+ return y
+
+def logspace(start,stop,num=50,endpoint=True,base=10.0):
+ """
+ Return numbers spaced evenly on a log scale.
+
+ In linear space, the sequence starts at ``base ** start``
+ (`base` to the power of `start`) and ends with ``base ** stop``
+ (see `endpoint` below).
+
+ Parameters
+ ----------
+ start : float
+ ``base ** start`` is the starting value of the sequence.
+ stop : float
+ ``base ** stop`` is the final value of the sequence, unless `endpoint`
+ is False. In that case, ``num + 1`` values are spaced over the
+ interval in log-space, of which all but the last (a sequence of
+ length ``num``) are returned.
+ num : integer, optional
+ Number of samples to generate. Default is 50.
+ endpoint : boolean, optional
+ If true, `stop` is the last sample. Otherwise, it is not included.
+ Default is True.
+ base : float, optional
+ The base of the log space. The step size between the elements in
+ ``ln(samples) / ln(base)`` (or ``log_base(samples)``) is uniform.
+ Default is 10.0.
+
+ Returns
+ -------
+ samples : ndarray
+ `num` samples, equally spaced on a log scale.
+
+ See Also
+ --------
+ arange : Similiar to linspace, with the step size specified instead of the
+ number of samples. Note that, when used with a float endpoint, the
+ endpoint may or may not be included.
+ linspace : Similar to logspace, but with the samples uniformly distributed
+ in linear space, instead of log space.
+
+ Notes
+ -----
+ Logspace is equivalent to the code
+
+ >>> y = linspace(start, stop, num=num, endpoint=endpoint)
+ >>> power(base, y)
+
+ Examples
+ --------
+ >>> np.logspace(2.0, 3.0, num=4)
+ array([ 100. , 215.443469 , 464.15888336, 1000. ])
+ >>> np.logspace(2.0, 3.0, num=4, endpoint=False)
+ array([ 100. , 177.827941 , 316.22776602, 562.34132519])
+ >>> np.logspace(2.0, 3.0, num=4, base=2.0)
+ array([ 4. , 5.0396842 , 6.34960421, 8. ])
+
+ Graphical illustration:
+
+ >>> import matplotlib.pyplot as plt
+ >>> N = 10
+ >>> x1 = np.logspace(0.1, 1, N, endpoint=True)
+ >>> x2 = np.logspace(0.1, 1, N, endpoint=False)
+ >>> y = np.zeros(N)
+ >>> plt.plot(x1, y, 'o')
+ >>> plt.plot(x2, y + 0.5, 'o')
+ >>> plt.ylim([-0.5, 1])
+ >>> plt.show()
+
+ """
+ y = linspace(start,stop,num=num,endpoint=endpoint)
+ return _nx.power(base,y)
+