Getting Naan error while integrating with multiple parameters

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Aakash Munnangi 2023-3-16

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https://ww2.mathworks.cn/matlabcentral/answers/1929525-getting-naan-error-while-integrating-with-multiple-parameters

编辑： VBBV 2023-3-16

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Hi, I am evaluating spectral radiance of a black body. It is giving me NaaN errors. The following is th

B =

h=6.63*(10^-34);
k=1.381*(10^-23);
c=3*(10^8);
T=6000;
fun = @(x) (2*h*(x.^3))./(c*c*((exp((h*x)./(k*T))-1)));    
x=integral(fun,380*(10^-9),750*(10^-9));
Warning: Inf or NaN value encountered.

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Answer 1

VBBV 2023-3-16

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1929525-getting-naan-error-while-integrating-with-multiple-parameters#answer_1194010

编辑：VBBV 2023-3-16

在 MATLAB Online 中打开

h=6.63*(10^-34);
k=1.381*(10^-23);
c=3*(10^8);
T=6000;
fun = @(x) (2*h*(c.^2)).*(x.^(-5)).*(exp((h.*c)./(k*x*T))-1).^(-1);    
x=integral(fun,380*(10^-9),750*(10^-9))

May be the equation you wrote is typed incorrectly. Check this link for planks law for black body/ solar radiation https://www.google.com/search?q=solar+irradiance+formula&prmd=isvn&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjQrZfhw9_9AhUEcGwGHd9ZAnAQ_AUoAXoECAIQAQ&biw=360&bih=676&dpr=2#imgrc=kK2Z1urXtXRX2M&lnspr=W10=

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Aakash Munnangi 2023-3-16

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I was able to correct it. here is the code. However, the energy version of Planks law definite integral giving valuee of 0. I think I am missing some precision. need help.

working version with wave lengths

h=6.63*(10^-34);
k=1.381*(10^-23);
c=3*(10^8);
T=6000;
lambda1 = 380*10^-9;
lambda2= 750*10^-9;
M_e = @(x) (2 * pi * h * c^2) ./ (x.^5 .* (exp((h * c)./(x * k * T)) - 1));
M_e_int1 = integral(M_e,lambda1,lambda2)
lambda1 = 0;
lambda2= Inf;
M_e = @(x) (2 * pi * h * c^2) ./ (x.^5 .* (exp((h * c)./(x * k * T)) - 1));
M_e_int2 = integral(M_e,lambda1,lambda2)
fraction_of_energy = M_e_int1/M_e_int2;

//Not working or giving value of 0 , for energy version of planc law integration.

h=6.63*(10^-34);
k=1.381*(10^-23);
c=3*(10^8);
T=6000;        
Energy_lower_limit = 100;
Energy_upper_limit = 10000;
M_e = @(x) (x.^3.*2)./((h^3 * c^2)*((exp(x/(k * T)) - 1)));
M_e_int1 = integral(M_e, Energy_lower_limit, Energy_upper_limit)

VBBV 2023-3-16

编辑：VBBV 2023-3-16

The energy version of planks law you are using may be incorrect. Check the values of input limits for energy being considered. Are they in same units ? Can you open a new question ?

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