Array Analysis

Calculate Array Differences

Calculate differences between consecutive array elements. 0th element of output is equal to x(0)- x(-1), where x(-1) is an optional scalar input that defaults to zero.

Calculate Array Sums

Calculate sums of consecutive array elements. 0th element of output is equal to x(0)+ x(-1), where x(-1) is an optional scalar input that defaults to zero.

Calculate Peak Moments

Calculate peak moments for an evenly sampled signal. 0th moment is the area under the peak i.e. the sum of the signals 1st moment is the location of the peak/centroid/center of mass. Calculated by sum(i*yi)/sum(yi), it's in units of the spacing between the signals, with 0 corresponding to the first element of the array. 2nd moment is the RMS peak width, also in index units.

Calculate Subdivision Sequence

Used when you want to bisect an interval recursively, at each step knowing the endpoints and midpoint e.g. for an interval of size 6 you get:

lowpoint-midpoint-highpoint
0-2-5
0-1-2
2-3-5
3-4-5

Edge Enhance 2D Array SGL

Perform an edge enhancement operation on a 2D array based on the absolute value of differences between neighbors of a point in opposite directions. It doesn't sharpen edges, but it does damp out constant regions.

Find Negative Edge

Search an array for a negative going zero crossing. Begin by searching backwards for a value above hysteresis value. Then search forwards for first value below zero.

Find Zero Crossings

Find the indices of points just after a zero crossing, searching either up or down in a waveform.

Mean Ignoring NaN

Calculate the mean of all non-NaN values in the array.

Remove DC Component

Subtract the mean from an array so the resulting array has a mean of 0.

Smooth 2D Array SGL

Perform a smoothing operation on a 2D array using a kernel like:
0 1 0
1 1 1
0 1 0
Element sums are normalized by the number of valid source elements, so a constant array would be unchanged.

Smooth Sum SGL

Sum operation for 2D array smoother. When encountering NaN, don't add it to the sum and decrement the count of items being summed.

Spline Interpolant with Derivative

Calculate the Spline Interpolant and also the first derivative of the spline curve.

Spline Interpolation with Derivative

Calculate spline and first derivative using pre-calculated interpolant.

Split Spectrum Filter

Perform split-spectrum filtering on the input waveform. FFT, overlapping gaussian parts, inverse FFT, and weight original time sequence with mean sq/variance.

Statistical Histogram

Create a histogram based on +/-3 standard deviations and outliers.

Sum Ignoring NaN

Sum a 2-D array of SGL, treating NaN as zero.

Zero Crossings Counter

Counts zero crossings in the specified direction, using Noise Threshold to provide some hysteresis.