Error in Smith chart code. What needs to be corrected? / What should be the correct code? The code was given to me, and it doesn't run on my laptop.

The error indicated by the code is as follows:

Error: File: SmithChart_final.m Line: 12 Column: 1

Function definitions are not permitted in this context.

The purpose of the activity is to create an interface or a program in MATLAB where it's possible to input certain data, which will be used to calculate other values. Subsequently, the goal is to graphically represent these calculations on a Smith chart.

%programa final
clear, clc, close all, format compact
%Ingreso de datos
fprintf('\n   Ingrese los datos soliciados en el formato Re+imj')
Z_0=input('\n* Impedancia caracteristica (Z0): ');
Z_L=input('\n* Impedancia de carga (ZL): ');
fprintf('\n   Zn se grafica con el punto rojo y Yn con el punto azul \n')

[Zn, Y, coef, vswr, PR, PD] = carta_calculo(Z_0, Z_L)

function carta_grafica
%grafica de carta de smith para ciruclos en "x" y "y"
t = linspace(0, 2*pi, 100);
x = cos(t);
y = sin(t);
plot(x, y,'-g.','linewidth',3,'markersize', 1); axis equal; 

title('------------------------ Smith Chart,Carta de Smith------------------------')
set(gca,'xticklabel',{[]});
set(gca,'yticklabel',{[]});
hold on 

k = [.25 .5 .75];
for i = 1 : length(k)
    x(i,:) = k(i) + (1 - k(i)) * cos(t);
    y(i,:) = (1 - k(i)) * sin(t);
    plot(x(i,:), y(i,:), 'k')
end 

kt = [2.5 pi 3.79 4.22];
k = [.5 1 2 4];
for i = 1 : length(kt)
    t = linspace(kt(i), 1.5*pi, 50);
    a(i,:) = 1 + k(i) * cos(t);
    b(i,:) = k(i) + k(i) * sin(t);
    plot(a(i,:), b(i,:),'k', a(i,:), -b(i,:),'k' )
end
end

function [Zn, Yn, coef, vswr, PR, PD] = carta_calculo(Zo, ZL) 
carta_grafica
Zn=ZL/Zo; 
Yn=1/Zn;
g=(Zn-1)/(Zn+1);
coef=abs(g);
th=angle(g);
ig=1/g;
ith=angle(ig);
%grafica para Zn y Yn
polar(th, coef, 'rx') %zn
polar(-ith, -coef, 'bx') %yn
thd= th * (180/pi); 

%VSWR
vswr=abs((1+coef)/(1-coef));
PR =-20*log10(coef);

PD=-10*log10(1-(coef)^2);
end

Answer 1

[Walter Roberson]

Your version of MATLAB, R2013a, is too old to be able to have function definitions in script files.

You will need to move function carta_grafica to file carta_grafica.m and need to move function carta_calculo to file carta_calculo.m

Or... you could update to a version of MATLAB that is not a decade old. R2015b is the release that started permitting functions in scripts.