MATLAB: Problem Calculating Nonlinear Indefinite Integral

MATLABnonlinear integration

Hello,

I am trying to calculate a nonlinear integral t^5.2 *exp((-x^6.2-x*(0.2*4.5^6.2))/4.5^6.2) in order to solve an equation, where the unknown is the lower limit of integrations.Although i use "int" in order to calculate the integral, Matlab returns the equation.Is my equation too complicated or there is another way to get a solution ?I am quite new in Matlab, so any help would be appreciated.

I would like to thank you in advance for the time dealing with my query.

Best Answer

Since you neglected to tell us values for a and b, I'll just set them to a=2 and b=1. You have also two definitions for g(x), so I've used the one in your code. Like the previous poster suggested, I'll embed integral inside fsolve:

g = @(x) x.^5.*exp((-x.^5-x*(4^6))/4^6) ;
Q = @(k) integral(g,k,k+2);
a = 2; b = 1; % Set these to whatever
k0 = 1; % Need a start guess here. 
k = fsolve(@(k) Q(k) - a/b, k0)

Related Solutions

MATLAB: Solving integral equations by integral

When using integral(), you don't need to use sym. Also exp is defined as a function in MATLAB, not a constant. Compare your code with the following code to find the mistakes

a=1.5;
b=0.5;
fun = @(x) (x-b).^2.*exp(-x);
value=integral(fun,0,a)

MATLAB: Fsolve not enough input arguments

You need to supply System() as a function handle to fsolve(). The way you have written it, Matlab thinks you want to simply call the function System(), and supply the result to fsolve().

As far as I know, the script itself should not execute because you can't define functions within scripts.

clc, clear
x0 = [1, 1, 1, 1,1];
Coefficients = fsolve(@(x)System(x), x0)

In a separate file (also, it looks like your function "System" will also not return an output, so need to change the output name):

function F = System(x)
F = nan(1,6);
F(1) = x(1)*[exp(x(4)/x(2)) - exp(-x(4)/x(3))] - 0.9;
F(2) = x(1)*[exp(-(x(4)-0.6*1.2e-6)/x(2)) - exp(-(x(4)-0.6*1.2e-6)/x(3))] - 0.3;
F(3) = x(1)*[exp(-50e-6/x(2)) - exp(50e-6/x(3))] - 0.5;
F(4) = x(1)*[exp(-x(5)/x(2)) - exp(-x(5)/x(3))] - 1;
F(5) = -x(1)/x(2)*exp(-x(5)/x(2)) + x(1)/x(3)*exp(-x(5)/x(3));
F(6) = 30e3*x(1)*(exp(-x(4)/x(2)-exp(-x(4)/x(3)))) - 30e3*x(1)*(exp(-(x(4)-0.6*1.2e-6)/x(2))-exp(-(x(4)-0.6*1.2e-6)/x(3)));
end

I would also ask about the math problem, which looks over-specified...5 unknowns in 6 equations

Best Answer

Related Solutions

MATLAB: Solving integral equations by integral

MATLAB: Fsolve not enough input arguments

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