finding a specific element based on conditions

Dear all,

I have two problems with my code.

1) The p table is filled in one row but I expected to have 100*4 table. as all variables have 100 rows.

2) I want to find a value in one column of my table if a condition in is satisfied in another column(both are in the same row). The condition is that if we reached to the last complex value in delta_teta column, I want to extract the value for K in the same row.

Please find a figure showing the problem more clearly attached.

Many thanks in advane.

K = generator(30,10,70);
a = 2.8;
B = 0.25;


r = radius_cal (K,B) ;
disp = disp_calc(B,K,a);
teta = atand( disp ./ a);
b = sqrt ((a .* a) + (disp .* disp)) ;
delta_teta = asind (b ./ (2 .* r)) .* 2;


for j = 1:numel(delta_teta)
x(j) = isreal(delta_teta(j));
end

reflected_muons=nnz(~x);
ratio_of_reflected = reflected_muons ./ numel(K);

AB1= array2table([K(:), r(:), disp(:), delta_teta(:) ]);
p=table (K,r,disp,delta_teta);
%colnames = {'Energy','Radius' ,'Displacement' ,'Δθ'};

writetable(AB1,'data.csv')


function r = radius_cal (K,B)
E0= my_const.m_mu_kg .* my_const.C .* my_const.C .* 6241506479963.2 ;
gamma = 1+ (K ./ E0);
v =  my_const.C * sqrt (1- (1./(gamma .* gamma)));
omega= ((my_const.q .* B) ./ my_const.m_mu_kg) .* sqrt (1- (v .* v) ./ (my_const.C .* my_const.C) );
r= v ./ omega;
end


function k=generator(start,step,quantity)
k=start+step*(0:quantity-1);
end

function disp = disp_calc(B,K,a)
E0= my_const.m_mu_kg .* my_const.C .* my_const.C .* 6241506479963.2 ;
gamma = 1+ (K ./ E0);
v =  my_const.C * sqrt (1- (1./(gamma .* gamma)));

omega= ((my_const.q .* B) ./ my_const.m_mu_kg) .* sqrt (1- (v .* v) ./ (my_const.C .* my_const.C) );
r= v ./ omega;
disp = r - sqrt ((r .* r) - (a .* a));
end

Answer 1

[Johan]

1) Your data are row vectors and not column vectors which is why your table statement does not lead to what you expect. Transposing the array in your table call should fix it.

K = generator(30,10,70);
a = 2.8;
B = 0.25;
r = radius_cal (K,B) ;
disp = disp_calc(B,K,a);
teta = atand( disp ./ a);
b = sqrt ((a .* a) + (disp .* disp)) ;
delta_teta = asind (b ./ (2 .* r)) .* 2;

Testing your imaginary numbers array wise is often more efficient but that's a detail considering the small size of your arrays

fun = @() realloop(delta_teta);
timeit(fun)

ans = 1.1317e-05

fun = @() realarray(delta_teta);
timeit(fun)

ans = 3.3761e-06

all(realarray(delta_teta) == realloop(delta_teta))

ans = logical
   1

2) for this you can use find to get the index of your last imaginary value in delta_theta:

x =  realarray(delta_teta);
i_index = find(not(x));
K(i_index(end))

ans = 120

reflected_muons=nnz(~x);
ratio_of_reflected = reflected_muons ./ numel(K);

AB1= array2table([K(:), r(:), disp(:), delta_teta(:) ])

AB1 = 70×4 table
    Var1     Var2          Var3               Var4     
    ____    ______    _______________    ______________

     30     1.1353    1.1353-2.5595i         90-88.924i
     40     1.3378    1.3378-2.4598i         90-78.443i
     50     1.5251    1.5251-2.3482i         90-69.704i
     60     1.7024    1.7024-2.223i          90-61.995i
     70     1.8723    1.8723-2.0819i         90-54.909i
     80     2.0369    2.0369-1.9212i         90-48.165i
     90     2.1972    2.1972-1.7356i         90-41.526i
    100     2.3542    2.3542-1.5159i         90-34.727i
    110     2.5084    2.5084-1.2441i         90-27.364i
    120     2.6604    2.6604-0.87299i        90-18.479i
    130     2.8105    2.5674+0i          85.036+0i     
    140     2.9591     2.002+0i          71.129+0i     
    150     3.1062    1.7614+0i          64.346+0i     
    160     3.2522    1.5979+0i          59.425+0i     
    170     3.3971    1.4735+0i          55.511+0i     
    180     3.5411    1.3733+0i          52.252+0i     

p=table (K',r',disp',delta_teta')

p = 70×4 table
    Var1     Var2          Var3               Var4     
    ____    ______    _______________    ______________

     30     1.1353    1.1353+2.5595i         90+88.924i
     40     1.3378    1.3378+2.4598i         90+78.443i
     50     1.5251    1.5251+2.3482i         90+69.704i
     60     1.7024    1.7024+2.223i          90+61.995i
     70     1.8723    1.8723+2.0819i         90+54.909i
     80     2.0369    2.0369+1.9212i         90+48.165i
     90     2.1972    2.1972+1.7356i         90+41.526i
    100     2.3542    2.3542+1.5159i         90+34.727i
    110     2.5084    2.5084+1.2441i         90+27.364i
    120     2.6604    2.6604+0.87299i        90+18.479i
    130     2.8105    2.5674+0i          85.036+0i     
    140     2.9591     2.002+0i          71.129+0i     
    150     3.1062    1.7614+0i          64.346+0i     
    160     3.2522    1.5979+0i          59.425+0i     
    170     3.3971    1.4735+0i          55.511+0i     
    180     3.5411    1.3733+0i          52.252+0i     

function r = radius_cal (K,B)
E0= my_const.m_mu_kg .* my_const.C .* my_const.C .* 6241506479963.2 ;
gamma = 1+ (K ./ E0);
v =  my_const.C * sqrt (1- (1./(gamma .* gamma)));
omega= ((my_const.q .* B) ./ my_const.m_mu_kg) .* sqrt (1- (v .* v) ./ (my_const.C .* my_const.C) );
r= v ./ omega;
end

function k=generator(start,step,quantity)
k=start+step*(0:quantity-1);
end

function disp = disp_calc(B,K,a)
E0= my_const.m_mu_kg .* my_const.C .* my_const.C .* 6241506479963.2 ;
gamma = 1+ (K ./ E0);
v =  my_const.C * sqrt (1- (1./(gamma .* gamma)));

omega= ((my_const.q .* B) ./ my_const.m_mu_kg) .* sqrt (1- (v .* v) ./ (my_const.C .* my_const.C) );
r= v ./ omega;
disp = r - sqrt ((r .* r) - (a .* a));
end

function out = realloop(in)
    out = zeros(1,numel(in));
    for j = 1:numel(in)
        out(j) = isreal(in(j));
    end
end

function out = realarray(in)
    out =  imag(in)==0;
end