my code doesnt show a graph even if i use the plot command

close all
clear all
h=[1:24];%hours in day
m=[1:14400];%minutes in day
n_param=5;
n=[1:365];%days in year
az=0.0001; % degrees  %a=0,001 , because a is near zero during sunrise and sunset.
ndec=355; %21 december is de 335e dag van het jaar
njul=202; %21 juli is de 202e dag van het jaar
p=52.3667; %altitude amsterdam
heigthblock=25; %heigth of the block in mETER
sino=zeros(1,365);
max_loops = 100;      
for n_days=n %azimuth angle
    sinoaz=-23.45*(pi/180)*cos(((2*pi)/365)*(10+n));
    oaz=asind(sinoaz);
    %wm=(m+7200)*pi/7200;
    %sin(a)=cos(o)*cos(wh)*cos(p)+sino*sin(p)
    %sin(a)-sino*sin(p)=cos(o)*cos(wh)*cos(p)
    %cos(wh)=(sin(a)-sino*sin(p))/((cos(o)*cos(p)))
    coswm=(sind(az)-(sinoaz*sind(p)))./((cosd(oaz).*cosd(p)));
    wmaz=acos(coswm);
    sinaaz=sind(az);
    sinAz=(sin(wmaz).*cosd(oaz))./sinaaz;
    A=asind(sinAz);
end
figure 
plot(n,A)

Answer 1

[Walter Roberson]

    sinoaz=-23.45*(pi/180)*cos(((2*pi)/365)*(10+n));

Should use n_days instead of n

A=asind(sinAz);

Should be

A(n_days)=asind(sinAz);

I have not executed your code but I also suspect that you might be generating complex-valued A values.

Answer 2

[Bhaskar R]

Here variable A is complex number. So MATLAB automatically recognise as complex value and plot as real values of the complex number

You can plot real and imaginary values together or individually or with repect to n

In your code there is no effect of for loop,

your code is

close all
clear all
h=[1:24];%hours in day
m=[1:14400];%minutes in day
n_param=5;
n=[1:365];%days in year
az=0.0001; % degrees  %a=0,001 , because a is near zero during sunrise and sunset.
ndec=355; %21 december is de 335e dag van het jaar
njul=202; %21 juli is de 202e dag van het jaar
p=52.3667; %altitude amsterdam
heigthblock=25; %heigth of the block in mETER
sino=zeros(1,365);
max_loops = 100;      
% for n_days=n %azimuth angle
    sinoaz=-23.45*(pi/180)*cos(((2*pi)/365)*(10+n));
    oaz=asind(sinoaz);
    %wm=(m+7200)*pi/7200;
    %sin(a)=cos(o)*cos(wh)*cos(p)+sino*sin(p)
    %sin(a)-sino*sin(p)=cos(o)*cos(wh)*cos(p)
    %cos(wh)=(sin(a)-sino*sin(p))/((cos(o)*cos(p)))
    coswm=(sind(az)-(sinoaz*sind(p)))./((cosd(oaz).*cosd(p)));
    wmaz=acos(coswm);
    sinaaz=sind(az);
    sinAz=(sin(wmaz).*cosd(oaz))./sinaaz;
    A=asind(sinAz);
% end
% real Vs imaginary of A
figure,plot(real(A), imag(A)),title('real Vs imaginary of A ') ;
 % n_days(n) Vs real of A
figure, plot(n, real(A)), title('n\_days(n) Vs real of A') ;
 % n_days(n) Vs imaginary of A
figure, plot(n, imag(A)), title('n\_days(n) Vs imaginary of A');

[Walter Roberson]

It does get confusing to be using a mix of degrees and radians in the calculations. It would be more consistent to use acosd for wmaz and sind(wmaz)

But would probably be even easier on people if deg2rad() was used on the parts that had to be in degrees (definition of az, and the -23.45 constant) and use radians everywhere else.

In particular look more carefully at the line

    sinoaz=-23.45*(pi/180)*cos(((2*pi)/365)*(10+n));

The -23.45*pi/180 is converting -23.45 degrees to radians, and the cos() part is producing radians, so sinoaz must be in radians, but on the next line you asind() it.