Switch Case with Loop

Hi!

I need help with this code:

clc;
clear;
close all;
a=input('Enter the real value of load impedance ZL, a=');
b=input('Enter the Imagninary value of load impedance ZL, b=');
ZL=a+1i*b;
disp(['ZL=',num2str(ZL),'ohm']);
a1=input('Enter the real value of characteristic Impedance Z0, a1=');
b1=input('Enter the imaginary value of characteristic Impedance Z0, b1=');
Z0=a1+1i*b1;
disp(['Z0=',num2str(Z0),'ohm']);
disp('Enter the R- To determine the Voltage reflection coefficient');
disp('Enter the V- To determine the VSWR');
disp('Enter the Z- to determine the impedance Zx from load');
c=input('Enter your choice','s');
switch c
    case 'R'
        rc=(ZL-Z0)/(ZL+Z0);
        x=real(rc);
        y=imag(rc);
        q=sqrt(x^2+y^2);
        VSWR=(1+q)/(1-q);
disp(['The VSWR is',num2str(VSWR)]);
    case 'Z'
        zx=Z0*((ZL+1i*Z0*tan((2*pi)*0.35))/(Z0+1i*ZL*tan((2*pi)*0.35)));
        disp(['The Zx from load ZL is ',num2str(zx),'ohm']);
    otherwise
        error('invalid choice');
end

I do not wish for the program to just end with an 'Invalid Choice' statement. I would like to program to loop back automatically prompting me to re-enter the parameters starting from Line 4. I am unsure on how to use syntaxes such as "if-else" or "for" or "while" to execute this. Please help!! Thank you :)

Answer 1

[KSSV]

c=input('Enter your choice','s');
while ~any(strcmp(c,{'R' 'Z'}))
    c=input('Enter your choice','s') ;
end
switch c
    case 'R'
        rc=(ZL-Z0)/(ZL+Z0);
        x=real(rc);
        y=imag(rc);
        q=sqrt(x^2+y^2);
        VSWR=(1+q)/(1-q);
        disp(['The VSWR is',num2str(VSWR)]);
    case 'Z'
        zx=Z0*((ZL+1i*Z0*tan((2*pi)*0.35))/(Z0+1i*ZL*tan((2*pi)*0.35)));
        disp(['The Zx from load ZL is ',num2str(zx),'ohm']);
end

[Lahiru Suraweera]

hi.

what about a switch statement with numerical cases. i only want input between 1 and 12 to be accepted.

c = input('Please enter the number of the conversion required: ');

switch (c)

case 1

whatever the program must do

case 2

whatever the program must do

...

case 12

whatever the program must do

otherwise

disp('invalid choice')

end

[Image Analyst]

That's fine. It can take pure numbers, like doubles, for the values on a "case" line.

Answer 2

[Image Analyst]

You might want to look at the menu() function.