linear interpolation of function handle

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Gianluca Angelini
Gianluca Angelini 2023-11-29
回答： Nipun 2023-12-21
Hi everybody, I need to calculate the value in the range pi <= wave_angle < pi/2 of the a function handle @(freq_wave,wave_angle) which is defined as:
((log(B/T))^-1).*(0.87/CB).^((1+Fn).*cos(wave_angle)).*(1/3-(2/3).*cos(wave_angle))
in the range ((wave_angle >=0) & (wave_angle <= pi/2))
((log(B/T))^-1).*(0.87/CB).^(1+Fn) in the range (wave_angle=pi)&(vel_nave>V_G(freq_wave)./2)&(Fn_rel(freq_wave)>=0.12)
((log(B/T))^-1).*(0.87/CB) in the range (wave_angle=pi)&(vel_nave<V_G(freq_wave)./2)+ ((log(B/T))^-1).*(0.87/CB) .*(wave_angle=pi)&(Fn_rel(freq_wave)<0.12);
but I don't konw which function is the best to use. Thanks in advance for your help.
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Gianluca Angelini
Gianluca Angelini 2023-11-29
Hi Torsten, thanks for you support. Your results are exactlay what the code do at this moment: I need to fill the empty space where the function a1 is not defined by interporlating its defintion between
((log(B/T))^-1).*(0.87/CB).^((1+Fn).*cos(wave_angle)).*(1/3-(2/3).*cos(wave_angle))
valid only for
((wave_angle >=0) & (wave_angle <= pi/2))
and
((log(B/T))^-1).*(0.87/CB).^(1+Fn) .*(vel_nave>V_G(freq_wave)./2)&(Fn_rel(freq_wave)>=0.12)) +...
((log(B/T))^-1).*(0.87/CB) .*((vel_nave<V_G(freq_wave)./2))+...
((log(B/T))^-1).*(0.87/CB) .*((Fn_rel(freq_wave)<0.12));
valid only for
(wave_angle==pi)
Torsten
Torsten 2023-11-29
编辑：Torsten 2023-11-29
And what should be the "interpolating" function ? It's completely arbitrary at the moment.

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回答（1 个）

Nipun
Nipun 2023-12-21
Hi Gianluca,
I understand that you are trying to evaluate a semantic relation, given the variable values. In the illustrated case, the equation to be used changes according to the range of the input.
It seems like you have a piecewise function defined over different ranges of wave_angle. In MATLAB, you can use the if, elseif, and else statements to define a piecewise function. The if statements can be used to check the conditions for each range and evaluate the corresponding expression.
Here is a code snippet to help you with the same:
function result = your_function(freq_wave, wave_angle, B, T, CB, Fn, vel_nave)
if wave_angle >= 0 && wave_angle < pi/2
result = ((log(B/T))^-1) .* (0.87/CB).^((1+Fn).*cos(wave_angle)) .* (1/3 - (2/3) .* cos(wave_angle));
elseif wave_angle == pi && vel_nave > V_G(freq_wave)/2 && Fn_rel(freq_wave) >= 0.12
result = ((log(B/T))^-1) .* (0.87/CB).^(1+Fn);
elseif wave_angle == pi && vel_nave < V_G(freq_wave)/2
result = ((log(B/T))^-1) .* (0.87/CB);
elseif wave_angle == pi && Fn_rel(freq_wave) < 0.12
result = ((log(B/T))^-1) .* (0.87/CB) .* (wave_angle == pi) .* (Fn_rel(freq_wave) < 0.12);
else
% Define default behavior if none of the conditions are met
result = NaN; % or any default value you prefer
end
end
This function checks the conditions for each range of wave_angle and evaluates the corresponding expression. You can adjust the conditions and expressions based on your specific requirements. The result variable holds the final value of the function for a given set of input parameters.
Since the signature and description of functions "Fn_rel" and others were not provided, I assume that they work as expected.
Hope this helps.
Regards,
Nipun

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