ENH: interpolate/polyint: allow polyint evaluation on arbitrary shape arrays
ENH: interpolate/polyint: make the polynomial interpolators able to deal with arbitrary-shape y data arrays
TST: interpolate/polyint: add tests for y-shape
BUG: interpolate/polyint: deal with complex-valued arrays
ENH: interpolate/polyint: refactor interpolation axis support in polyint

Support dealing with the interpolation axis using the same mechanism in
all of the interpolators.
MAINT: interpolate/polyint: rename Pchip -> PchipInterpolator
BUG: interpolate/polyint: fix divisions by zero in pchip
STY: interpolate/polyint: make the code a bit more readable
ENH: interpolate/polyint: make the derivative axis be always first in the derivatives() methods
DOC: interpolate: update the polyint documentation to match the implementation vs. axis and shapes
STY: interpolate/polyint: rename InterpolatorBase -> _Interpolator1D
added norm examples to linalg.rst docs
better comments to example, use np.array instead of matrix
ENH: signal: spectral: Add periodogram and welch functions
converted linalg.rst to use mat except for schur factorization, explained numpy.linalg vs scipi.alg, examplained numpy.ndarray vs numpy.matrix
BUG: signal: spectral: fix various bugs in periodogram and welch.

1. various off by 1 issues in dealing with the output of fftpack.rfft.
2. the DC and nfft/2 points shouldn't be scaled by 2 for 'onesided'
3. error in computing frequency axis in 'onesided'

The output of welch exactly matches matplotlib.mlab.psd for both even
and odd length  one-sided spectra and even length two-sided spectra of
real data.  For odd length two-sided spectra of real data, welch matches
the spectrum but matplotlib.mlab.psd return an incorrect frequcny axis.
BUG: signal: spectral: Fix bug introduced in last commit

We want fftbins=True in signal.get_window.  matplotlib.mlab.psd
effectively uses fftbin=False since this option doesn't exist in numpy.
Swapped this in to do some testing.
ENH: stats.scoreatpercentile

stats.scoreatpercentile now accepts sequences of percentiles and axis
parameter. Function adapted from NumPy's percentile function.
ENH: signal: spectral: Support detrending in welch.
MAINT: signal:  update binary attrib on _spectral.c

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