Question

I have three vectors A, B, and C. For each value in these vectors I would like to solve the equation C^x = A^x + B^x. Unfortunately this is an equation that I have found to be solvable only iteratively, so I am attempting to use MATLAB’s “solve” function to find a solution for each case. My code is as follows:

exponents = zeros(100,1);

syms x

A = rand(100,1);
B = rand(100,1);
C = rand(100,1);

for i = 1:100

exponents(i) = eval(solve(C(i)^x == A(i)^x + B(i)^x));

end

Sometimes, however, the solution is unobtainable, which leads to the error message, “Warning: Explicit solution could not be found.” I am okay with this, but if I run into an unsolvable equation, I would like to simply leave the “exponents(i)” unchanged for that iteration and move onto the next one, instead of having my code abruptly stop. Any suggestions?

Answer 1

If you put the statement that causes the occasional error inside a try/catch statement, then the error will not cause execution to stop. For example, you could try:

for i = 1:100
  try
    exponents(i) = eval(solve(C(i)^x == A(i)^x + B(i)^x));
  catch
    exponents(i) = NaN; 
  end;
end