Problem using the 'subs' command(Error using symengine)

I am trying to solve the cubic equation 0.75*k*B1^3 -m*w^2*B1 + c*B1 - A == 0 and get the absolute number for the roots. However, I encounter "Error using symengine" when I try to use replace the 'k' symbolic variable with 0 using 'subs' command. Below is my code. There is no problem if I enter some value other than 0 in the code.

syms A m c k w B1

eqn = 0.75*k*B1^3 -m*w^2*B1 + c*B1 - A == 0

sol = solve(eqn,B1)

root = abs(subs(sol, [k,m,c,A], [0,1,1,1]))

And below is the errors that I got:

Error using symengine The third argument must be an integer between 1 and the degree of the polynomial.

Error in sym/subs>mupadsubs (line 140) G = mupadmex('symobj::fullsubs',F.s,X2,Y2);

Error in sym/subs (line 125) G = mupadsubs(F,X,Y);

Error in NonlinearStudy (line 9) root = abs(subs(sol, [k,m,c,A], [0,1,1,1]))

Answer 1

[Birdman]

You should use subs command for coefficients before solving the equation.

syms A m c k w B1
eqn = 0.75*k*B1^3 -m*w^2*B1 + c*B1 - A == 0
eqn = subs(eqn,{k,m,c,A},{0,1,1,1})
sol = solve(eqn,B1)