What is wrong in script?

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Athira T Das 2022-7-23

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1766125-what-is-wrong-in-script

编辑： Torsten 2022-7-25

for m1 =0:M
    T2=0;
    for m2=0:M
        T3=0;
        for s1=0:m1/2
            T4=0
            for j1=0:m1-2*s1
                T5=0
                for s2=0:(M-m1)/2
                    T6=0;
                    for j2=0:(M-m1-2*s2)
                        T6=T6+(1/(po^2))^j2;
                    end
                    T5=T5+T6*((2*1i)/(delta^(0.5)))^(M-m1-2*s2);
                end
                T4=T4+T5*(1/(po^2))^j1;
            end
            T3=T3+T4*((2*1i)/(delta^(0.5)))^(m1-2*s1);
        end
        T2=T2+T3*(factorial(M)/(factorial(m2)*factorial(M-m2)));
    end
    T1=T1+T2*(factorial(M)/(factorial(m1)*factorial(M-m1)));
end

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Torsten 2022-7-24

在 MATLAB Online 中打开

k = 5.9275e+06

And why do you write

rho = (0.545*z)^(-3/5)

instead of

rho = (5.9275e+06^2*z)^(-3/5)

in your formula ?

Athira T Das 2022-7-24

Ok. But I am confused whether my for loops are working properly or not?

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回答（1 个）

Torsten 2022-7-24

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1766125-what-is-wrong-in-script#answer_1013980

编辑：Torsten 2022-7-24

在 MATLAB Online 中打开

I would have progrmmed it this way, but the result seems to be the same.

My guess is that there is a mathematical trick to extremely simplify the expression (something like sum_{i=0}^(i=n} nchoosek(n,i) * p^i * (1-p)^(n-i) = 1), but I don't see it at the moment.

M = 3;
w = 0.2;
z = 0:10000;
k = 5.9275e+06;
Po = (k^2*z).^(-(3/5));
Delta = 1i*k./(2*z) + 1/w^2 + 1./Po.^2;
po = Po(1);
delta = Delta(1);
X = 0;
for m1 = 0:M
  faktor = nchoosek(M,m1);
  sum1 = 0.0;
  for s1 = 0:m1/2
    faktor1 = (2*1i/sqrt(delta)).^(m1-2*s1);
    sum_inner = 0.0;
    for j1 = 0:m1-2*s1
      sum_inner = sum_inner + (1/po^2)^(j1);
    end
    sum1 = sum1 + faktor1*sum_inner;
  end
  sum2 = 0.0;
  for s2 = 0:(M-m1)/2
    faktor2 = (2*1i/sqrt(delta)).^(M-m1-2*s2);
    sum_inner = 0.0;
    for j2 = 0:M-m1-2*s2
      sum_inner = sum_inner + (1/po^2)^(j2);
    end
    sum2 = sum2 + faktor2*sum_inner;
  end  
  X = X + faktor*sum1*sum2;
end
X = X*2^M
X = 0

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Athira T Das 2022-7-25

在 MATLAB Online 中打开

@Torsten

If any terms depends on m2, can I write the code like

for m1 = 0:M
    faktor = nchoosek(M,m1);
  for m2 = 0:M
    faktor0 = nchoosek(M,m2);
    .......................................
        ....................................
         X = X + faktor0.*sum1.*sum2;
  end
  X = X*faktor
end

Torsten 2022-7-25

编辑：Torsten 2022-7-25

在 MATLAB Online 中打开

I think something like this:

M = 6;
w = 0.2;
z = 0:10000;
k = 5.9275e+06;
Po = (k^2*z).^(-(3/5));
Delta = 1i*k./(2*z) + 1/w^2 + 1./Po.^2;
po = Po(1);
delta = Delta(1);
X = 0;
for m1 = 0:M
  faktor_m1 = nchoosek(M,m1);
  sum_m2 = 0.0;
  for m2 = 0:M
    faktor_m2 = nchoosek(M,m2);
    sum1 = 0.0;
    for s1 = 0:m1/2
      faktor1 = (2*1i/sqrt(delta)).^(m1-2*s1);
      sum_inner = 0.0;
      for j1 = 0:m1-2*s1
        sum_inner = sum_inner + (1/po^2)^(j1);
      end
      sum1 = sum1 + faktor1*sum_inner;
    end
    sum2 = 0.0;
    for s2 = 0:(M-m1)/2
      faktor2 = (2*1i/sqrt(delta)).^(M-m1-2*s2);
      sum_inner = 0.0;
      for j2 = 0:M-m1-2*s2
        sum_inner = sum_inner + (1/po^2)^(j2);
      end
      sum2 = sum2 + faktor2*sum_inner;
    end 
    sum_m2 = sum_m2 + faktor_m2*sum1*sum2;
  end
  X = X + faktor_m1*sum_m2;
end
X
X = 2048