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

4 次查看（过去 30 天）
인석 문
인석 문 2021-5-4
回答： Star Strider 2021-5-4
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

请先登录，再回答此问题。

采纳的回答

Star Strider
Star Strider 2021-5-4
Ran in:
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!

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Conversion Between Symbolic and Numeric 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by