want to find the values of 'K' for which the function (D) becomes zero. 'L' and 'a' are the constants. Code:
D = [cosh(K*L)-cos(K*L), sinh(K*L)-sin(K*L); sinh(K*L)+sin(K*L)+K*a*L*(cosh(K*L)+cos(K*L)), cosh(K*L)-cos(K*L)+K*a*L*(sinh(K*L)+sin(K*L))];
Error using fzero (line 309) Function value at starting guess must be finite and real.