# Utilities

CorrelationFunctions.read_cuboidFunction
read_cuboid(cfgpath :: String)

Read 3D array from a disk. The data on disk consists of two files: JSON configuration file (which is passed to this function) and a raw binary array data.

Scheme of the configuration file is as follows, where x, y and z are dimensions of the array:

{
"dimensions": [x, y, z],
"datapath": "file-with-data"
}

The file with binary data, whose name is specified in datapath field, is searched relatively to the directory with the JSON configuration file. Its size must be exactly xyz bytes, each byte containing an element of the resulting array.

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read_cuboid(datapath :: String, side, dim)

Read 3D array from a disk. The data on the disk must be in binary format, one octet per sample. Totally, there must be $side^{dim}$ octets which are read into $side \times side \times \dots \times side$ array.

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CorrelationFunctions.Directional.lowfreq_energy_ratioFunction
lowfreq_energy_ratio(array, fraction = 0.5)

Calculate a ratio $E_a/E$ where $E$ is a total energy of a signal array and $E_a$ is the energy concentrated in frequencies $[0, af/2]$ where $f$ is the sampling rate and $a$ is set via parameter fraction. mean(array) is subtracted from the array before calculations.

This function can be helpful in estimating if array is suitable for calculating surface-surface or surface-void function. An empirical criterion is that if this function returns a value greater than 0.95, the array is good.

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