What does "undefined eq" means on fixed.Interval command

Hello, I'm trying to write a switch case with intervals but I keep gettin this error: Undefined function 'eq' for input arguments of type 'fixed.Interval'. I don't know what that means. I'll attatch the code I'm trying to run.

unitVc=app.DropDownVC.Value; 
            switch unitVc
                case app.Vc.Value==fixed.Interval(0,60)
                    f=warndlg('El Volumen de carga debe ser menor o igual a 60 L');
            end

UnitVc, DropDownVc and app.Vc.Value were previously defined. Thanks

Answer 1

[Walter Roberson]

switch true
    case ~contains(fixed.Interval(0,60), unitVc)

but are you sure it is wise to use the Fixed Point Designer facilities for a UI task? Wouldn't it make more sense to test

switch true
    case unitVc < 0 | unitVc > 60

[Giulia Di Giorgio]

Thank you, you are right, the second command is wiser, but I'm having trouble when using multiple cases in one switch, it only reads the first switch. Code below

switch true
            case unitVc < 0 | unitVc > 60 &'L'
            f=warndlg('El Volumen de carga debe ser menor o igual a 60 L');
            case unitVc < 0 | unitVc > 0.06 & 'm³'
            f=warndlg('El Volumen de carga debe ser menor o igual a 0.06 m³');
            end

[Walter Roberson]

Does your dropdown have entries such as '100L' or '100 L' ? Entries such as '0.03 m³' in the same dropdown ?? Entries with negative numbers ?? Entries where the number is not the first thing in the entry?

If your entries are text then you should

Vc_okay = false;
switch unitVc
    case {'-400 L', '-0.4 m³', '0 L', '0 m³', '75 L', '0.75 m³', '100 L', '1 m³', '250 L', '2.5 m³'}
       f = warndlg('El Volumen de carga debe ser menor o igual a 60 L / 0.06 m³');
    otherwise
       Vc_Okay = true;
end

[Giulia Di Giorgio]

No, I'm going to attach my app so I can show you how it looks. I have to units: L and m³ and I want that volume to be between 0 and 60 liters or 0 and 0.06 m³, that's what I tried to program on the code above.