fitPowerLawParams
Fit power law absorption parameters for highly absorbing media.
Syntax
[a0_fit, y_fit] = fitAbsorptionValues(a0, y, c0, f_min, f_max) [a0_fit, y_fit] = fitAbsorptionValues(a0, y, c0, f_min, f_max, plot_fit)
Description
fitPowerLawParams calculates the absorption parameters that
should be defined in the simulation functions given the desired power law absorption behaviour defined by a0 and y. This takes into account the actual absorption behaviour exhibited by the fractional Laplacian wave equation.
This fitting is required when using large absorption values or high frequencies, as the fractional Laplacian wave equation solved in kspaceFirstOrder1D, kspaceFirstOrder2D, kspaceFirstOrder3D, and kspaceSecondOrder no longer encapsulates absorption of the form a = a0*f^y.
The returned values should be used to define the medium.alpha_coeff and medium.alpha_power within the simulation functions. The absorption behaviour over the frequency range f_min:f_max will then follow the power law defined by a0 and y.
Inputs
a0 |
desired power law absorption prefactor [dB/(MHz^y cm)] |
y |
desired power law exponent |
c0 |
medium sound speed [m/s] |
f_min |
minimum frequency of interest [Hz] |
f_max |
maximum frequency of interest [Hz] |
Optional Inputs
plot_fit |
Boolean controlling whether the final fit is displayed (default = false) |
Outputs
a0_fit |
power law absorption prefactor that should be used to define medium.alpha_coeff in the simulation functions |
y_fit |
power law exponent that should be used to define medium.alpha_power in the simulation functions |