Module util

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util.py - classes and functions that are not specific to the calculation methods.

Functions

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air_properties(T)
Properties of air as a function of temperature

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calculate_interval_in_cents(f1, f2)
Calculate the interval in cents between two frequencies.

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calculate_ratio_in_db(A1, A2)
Calculate the ratio in dB between two values.

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transform_R2Z(R)
Convert reflection coefficient to normalized impedance

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transform_Z2R(Z)
Convert normalized impedance to reflection coefficient

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equivalent_length(R, k)
Return the equivalent length of a complex reflection coefficient R: reflection coefficient k: wavenumber

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load_or_calculate(filename, func, **args)
Function that will load a backup of the results if available, otherwise it calculates the function and save the results.

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__create_equal_tempered_scale()

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Variables

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EQUAL_TEMPERED_SCALE = {'A0': 27.5, 'A0 flat': 25.9565435987, ...

Function Details

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air_properties(T)

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Properties of air as a function of temperature

The formula, valid for ±10 Celcius around 26.85 C, comes from Table 1 of reference 1.

References:

Keefe, D. H. (1984). Acoustical wave propagation in cylindrical ducts: Transmission line parameter approximations for isothermal and nonisothermal boundary conditions. J. Aoucst. Soc. Am., 75(1), 58-62.

TODO: look for a more recent source to double check the validity

Variables Details

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EQUAL_TEMPERED_SCALE

Value:

{'A0': 27.5,
 'A0 flat': 25.9565435987,
 'A1': 55.0,
 'A1 flat': 51.9130871975,
 'A2': 110.0,
 'A2 flat': 103.826174395,
 'A3': 220.0,
 'A3 flat': 207.65234879,
...