empty sym: 0-by-1. please help me

a=9.61;

b=0.16;

fc=2000*10^6;

c=300*10^6;

A= 10^(1/10)-10^(20/10);

B=(20*log10(4*pi*fc/c))+10^(20/10);

syms R real;

y=(A/(1+a*exp(-b*(atand(500/R)-a))))+20*log10(R/(cosd(atand(500/R))))+(B)-10^10==0

sol=solve(y,R)

This is my scropt. I want to solve this equation, But mine gives me an Empty sym: 0-by-1 error whenever I try to run it.

Please help me

Answer 1

[Star Strider]

a=9.61;
b=0.16;
fc=2000*10^6;
c=300*10^6;
A= 10^(1/10)-10^(20/10);
B=(20*log10(4*pi*fc/c))+10^(20/10)

B = 138.4624

syms R real;
y=(A/(1+a*exp(-b*(atand(500/R)-a))))+20*log10(R/(cosd(atand(500/R))))+(B)-10^10

y = 

yfcn = matlabFunction(y)

yfcn = function_handle with value:
    @(R)(log(R.*sqrt(1.0./R.^2.*2.5e+5+1.0)).*2.0e+1)./log(1.0e+1)-9.874107458820583e+1./(exp((atan(5.0e+2./R).*(-1.44e+2./5.0))./pi+9.61e+2./6.25e+2).*(9.61e+2./1.0e+2)+1.0)-9.999999861537628e+9

Rv = linspace(-1E+4, 1E+4);
figure
plot(Rv,real(yfcn(Rv)))
grid

% ylim([min(ylim) 1])

figure
plot(Rv,imag(yfcn(Rv)), '-r', 'LineWidth',2)
grid
ylim([-5  max(ylim)])

There is no solution because the function never crosses 0 on either the real or imaginary axes!