# Anonymous Functions in Matlab

There is a way to create a one-line expression-based MATLAB function that does not require a program file. It is called an anonymous function. The following very simple example shows how it works.

%% EXAMPLE n.1 % square function my_sqr = @(x) x.^2; my_sqr(4) % returns 16

It is very useful when you want to calculate the values without storing them to a variable (vector, or matrix) while keeping the code simple (without creating another program file).

%% EXAMPLE n.2 % Butterworth filter % define the frequency axis freq_axis = logspace(1,3,1000); % define the function that calculates the FRF function (in dB) % of a Butterworth filter Butterworth_FRF = @(f,n,fc) 20*log10(1./(1+(f/fc).^n)); % plot the FRF for different orders n fc = 100; % cut-off frequency of a Butterworth filter for n = 1:5 semilogx(freq_axis,Butterworth_FRF(freq_axis,n,100),'linewidth',2,'Displayname',['order = ' num2str(n)]); hold on end legend('show','location','southwest'); grid on ylim([-50 0]); xlabel('Frequency [Hz]'); ylabel('Gain [dB]');