quantfilt1

qx = quantfilt1(x, quantile, span, [tail_option])

quantfilt1() is a span-order quantile filter for one-dimensional arrays
quantile is the proportion of the window data whose value is returned at the center of each window
span is the filter order (window size)

quantile range: [0 to 1] Examples: 0.0 == local minimum filter
0.5 == local median filter
1.0 == local maximum filter

For odd span, qx(i) is the quantile value of x((i - ((span - 1) / 2)) : (i + ((span - 1) / 2)))
For even span, qx(i) is the quantile value of x((i - ((span - 2) / 2)) : (i + (span / 2)))

Tail half-windows are treated with the following options:
'truncate': fill with the quantile values of progressively shrinking windows (default)
'extrapolate': fill with the quantile values of closest full window
'zeropad': fill with zeros