MATLAB: Inverse of algebraic expression in Matlab

equation

I need to get inverse expression of the following algebraic expression in matlab.
clc;
clear;
syms r
E(r)= 1-1/2*((1+r)*log2(1+r)+(1-r)*log2(1-r));
g=finverse(E)
Using this command no output is there. I need to see the expression of r in terms of E. Is there any way to get that. Pl somebody help me.
output is 
g(r) =
 
Empty sym: 0-by-1

Best Answer

Possibly: 
rfcn = @(E) fsolve(@(r) 1-1/2*((1+r).*log2(1+r)+(1-r).*log2(1-r)) - E, 10);     % Anonymous Function: r(E)
N = 200;
Ev = linspace(0, 1, N);                                                         % Sample  E’ Vector
for k = 1:numel(Ev)
    r(k) = rfcn(Ev(k));
end
figure
plot(Ev, real(r),    Ev, imag(r))
grid
gama = linspace(-1, 1, N);
[Gama,Rm] = ndgrid(gama,r);
G = @(r,gama) atan(r.*tan(N*gama)); %% r is  [0,1];
g = @(r,gama) atan(r.*tan(gama)); %% gama is also [-1,1];
Delta=G(Rm,Gama)-N*g(Rm,Gama);
figure
meshc(gama, Ev, real(Delta))
grid on
xlabel('\gamma')
ylabel('E')
zlabel('\Delta')
view(125,25)
and:
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