Solving a single variable equation in R using unitroot

Question

I have a complicated equation for which I have written the code as follows:

sigma = 1.336449027;
f_t = 0.500185113;
alpha = 0.364; #elasticity of capital
beta = 0.115; #elasticity of labor
R = 3.131696599;
chi = 0.5;
M = log(1056);
sigma = 1.336449027; #degree of product substitutability
W = log(29448.08908);
P = 3.0686;
aval = 1.25;
c = 0.5;


f = function(b){
  loutpow = sigma/(beta*(sigma-1)-sigma);
  lconst1 = sigma/(beta*(sigma-1));
  lconst2 = (aval*kval^alpha)^((1 - sigma)/sigma);
  lconst3 = (R*P^(sigma-1))^(1/sigma);
  lval = (W/b*lconst2/lconst3*lconst1)^loutpow;
  profit_first_term = (R*P^(sigma-1))^(1/sigma)*(aval*kval^alpha*lval^beta)^(1-(1/sigma));
  profit_middle_terms = kval - kprimeval - f_t*kprimeval - c(kval - kprimeval)^2
  profit_last_term = W/b*lval
  profit =  profit_first_term + profit_middle_terms - profit_last_term
  bankruptcy = profit - chi*dval
}

For a range of kval,kprimeval,dval from 1 to 10000, I want to find the roots of this equation, that is the value of b. It is possible that for some values of kval,kprimeval,dval roots do not exist.

Answer 1

apparently your function has not a zero:

curve(f(x), -1, 1e9)