why my figure doesn't show the same logarithmic response like the one in the attached figure?.

figure
%set(gca, 'XScale', 'log')
%set(gca, 'YScale', 'log')
ylim ([0 16])
APD=linspace(0,2);
%APD=0:0.5:2;
for ii=1:3                                                
    if ii == 1   
        f=25.4;    
        color = 'k';
        style='-';
        linewidth = 2;
        hold on
        
    elseif ii == 2 
        f=35;
        color = 'b';
        style = '-';
        linewidth = 2;
        
    elseif ii == 3
        f=50;    
        color = 'g';
        style = '-';
        linewidth = 2;
        
    end
    phi_SAFOV = atand((APD.*10^-4)./(2*f*10^-3));   
    set(gca,'XTICK',[ 0 0.5 1 1.5 2 ]);
    set(gca,'YTICK',[ 0 2 4 6 8 10 12 14 16 ]);
    plot(APD,phi_SAFOV,'Color',color,'LineStyle',style,'linewidth',linewidth);
    lgd = legend('f=25.4 mm','f=35.0 mm','f=50.0 mm','off');
end
hold off
xlabel('Surface area of PD (cm^2)')
ylabel('\oslash_v_e_r or \oslash_h_o_r (^o)')

Answer 1

[Dave B]

I'm not sure how to match the y axis values, your equation didn't have much info about DPD, but it looks to me like you're missing a sqrt (maybe because the x axis is cm^2?)

(In any case I cleaned up your code :) )

x=linspace(0,2);
f=[25.4 35 50];
phi_SAFOV = atand(sqrt(x)./(2*f'));   
plot(x,phi_SAFOV,'linewidth',2); 
colororder(diag([1 1 1]))
legend('f=25.4 mm','f=35.0 mm','f=50.0 mm','Location','north');
xlabel('Surface area of PD (cm^2)')
ylabel('\oslash_{ver} or \oslash_{hor} (^o)')

[ORION OMN]

I missed the sqrt, it works well now with "ylim ([0 16])".

Thank you for your time and for cleaning my code. ^-^