MATLAB: How can i solve these two equations simultaneously for A and B

bessele functionequationintegrationsolvesymbolic

I have a system of 16 equations with 4 integration constants (A, B, C and D) in each soil layer (4 layers) and each soil layer has 4 stress-strain equations. I need to solve them simultaneously for 16 constants.

Below is the simplified form of two equations, which i am trying to solve for A and B.

int(5*besselj(0,x)*besselj(1, 0.5*x)*x*(A+5) ,x,0,10) = 0;

int(5*besselj(0,x)*besselj(1, 0.8*x)*x*(A+B) ,x,0,10) = A;

Best Answer

The multiply by (A+5) in the first equation leads to the trivial solution A=-5, zeroing the effect of the besselj .

You can substitute A into the second equation and then do a numeric solve, restriction your range for B from 5 onwards; the numeric solution turns out to be about B = 5.57463755753316

Related Solutions

MATLAB: How to add a matrix element in a fzero function

As you wrote it, the function is the literal text including the argument so nothing ever gets substituted for dynamically--one way that mimics yours directly but does get the current value of J() would be

...
for i = 1:n
  fnA=@(x) x*besselj(1,x)/besselj(0,x)-J(i);
  A(i,n)=fzero(fnA,0);
end

that embeds current J(i) into the function handle.

I just used a constant zero for the initial guess, that worked for the first couple; I didn't check if need better for the full range...

MATLAB: How can i solve a function for A, a constant ……… if the function’s intragrand is (x +A) and limits are 0 – 10 when function==0 ???

Just do exactly what you said. WTP?

See that:

syms x A
int(x+A,x,[0,10])
ans =
10*A + 50

Then in one line:

solve(int(x+A,x,[0,10]) == 0,A)
ans =
-5

Best Answer

Related Solutions

MATLAB: How to add a matrix element in a fzero function

MATLAB: How can i solve a function for A, a constant ……… if the function’s intragrand is (x +A) and limits are 0 – 10 when function==0 ???

Related Question