elegant solution to address an element of an array [newbie]

[BVBA NuKey Music]

I am looking for  a more elegant solution to the following problem
f=26e3:0.1:31e3;
An=2*A*abs(sin(pi*f*50e-6))./(pi*400e-6*f);
%I then look for the index of the value corresponding with f=27500
%In fact I first wrote f27500_i=find(27500=f), but that doesn't work:
f27500_i=find((27499.9<f) & (f<27500.1));
%determine value of An for 27500Hz in dB
fprintf('value of An for 27500Hz in dB is:'),disp(20*log10(An(f27500_i)/sqrt(2)))

thanks in advance
nukey