Using the drop down box in app designer

Hi, I am trying to assign values to different options in a drop down menu and then calculate reverb time using a formula. It is spitting out the wrong values as it is not recognising CA, WA and FM (only starting off so sorry if its blindingly obvious)

% Button pushed function: Button2
function Button2Pushed(app, event)
value = app.WallMaterialDropDown.Value;
value = app.FloorMaterialDropDown.Value;
value = app.CeilingMaterialDropDown.Value;
WA = app.WallMaterialAbsoprtionCoeffecientEditField.Value;
CA = app.CeilingMaterialCoeffiicientEditField.Value;
FA = app.FloorMaterialCoefficientEditField.Value;

if app.FloorMaterialDropDown.Value == strcmp(value,'Concrete or Tile')
    FA = 0.02;
    app.FloorMaterialCoefficientEditField.Value = FA;
elseif app.FloorMaterialDropDown.Value == strcmp(value,'Linoleum/ Vinyl Floor On Concrete')
    FA = 0.03;
    app.FloorMaterialCoefficientEditField.Value = FA;
elseif app.FloorMaterialDropDown.Value == strcmp(value,'Wood on Joists')
    FA = 0.07;
    app.FloorMaterialCoefficientEditField.Value = FA;
elseif app.FloorMaterialDropDown.Value == strcmp(value,'Parquet on Concrete')
    
    FA = 0.06;
    app.FloorMaterialCoefficientEditField.Value = FA;
elseif app.FloorMaterialDropDown.Value == strcmp(value,'Carpet on Concrete')
    
    FA = 0.37;
    app.FloorMaterialCoefficientEditField.Value = FA;
elseif app.FloorMaterialDropDown.Value == strcmp(value,'Carpet on foam')
    
    FA = 0.69;
    app.FloorMaterialCoefficientEditField.Value = FA;
elseif app.FloorMaterialDropDown.Value == strcmp(value,'6mm carpet')
    FA = 0.31;
    app.FloorMaterialCoefficientEditField.Value = FA;
end
if app.WallMaterialDropDown.Value == strcmp(value,'Brick Unglazed')
    
    WA = 0.04;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value,'Sheetrock 1/2"')
    
    WA = 0.04;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value,'Wood 3/8 Plywood Panel')
    
    WA = 0.09;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value,'Marble and Tile ')
    
    WA = 0.01;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value,'Plaster Rough on Lath')
    
    WA = 0.05;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value,'Plaster Smooth On Brick')
    
    WA = 0.03;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value,'Glass: Window')
    
    WA = 0.12;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value,'Foam: Polyur 1"')
    
    WA = 1.00;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value, 'Foam Polyur 1/2"')
    
    WA = 0.60;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value, 'Glass 1/4 large plate')
    
    WA = 0.03;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value, 'Foam SDG 3"')
    
    WA = 0.91;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value, 'Foam SDG 4"')
    
    WA = 0.99;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value, 'Fiberglass 5" sprayed')
    
    WA = 0.70;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value, 'Fibreglass 2" rolls')
    
    WA = 0.90;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value, 'Foam Sonex 2"')
    
    WA = 0.81;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value,'Fiberglass 1" sprayed')
    
    WA = 0.90;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value,'Fiberglass ')
    
    WA = 0.99;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value,'Curtain 18oz')
    
    WA = 0.72;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value, 'Fiberglass 2" No gaps')
    
    WA = 0.99;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value, 'Curtain 14"')
    
    WA = 0.75;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value, 'Brick Unglazed and Painted')
    
    WA = 0.02;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value, 'Concrete Block Coarse')
    
    WA = 0.29;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value, 'Concrete Block Painted')
    WA = 0.07;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value, 'Curtain 10oz')
    WA = 0.17;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value, 'Rockwool')
    WA = 0.9;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
elseif app.WallMaterialDropDown.Value == strcmp(value, 'Hard Surface')
    WA = 0.03;
    app.WallMaterialAbsoprtionCoeffecientEditField.Value = WA;
end
if app.CeilingMaterialDropDown.Value == strcmp(value,'Acoustic Tiles')
    CA = 0.56;
    app.CeilingMaterialCoeffiicientEditField.Value = CA;
elseif app.CeilingMaterialDropDown.Value == strcmp(value, 'Acoustic Ceiling Tiles')
    CA = 0.92;
    app.CeilingMaterialCoeffiicientEditField.Value = CA;
elseif app.CeilingMaterialDropDown.Value == strcmp(value, 'Fibreglass 2" no airspace')
    CA = 0.99;
    app.CeilingMaterialCoeffiicientEditField.Value = CA;
elseif app.CeilingMaterialDropDown.Value == strcmp(value, 'Fibreglass Spray 5"')
    CA = 0.70;
    app.CeilingMaterialCoeffiicientEditField.Value = CA;
elseif app.CeilingMaterialDropDown.Value == strcmp(value, 'Fibreglass spray 1"')
    CA = 0.90;
    app.CeilingMaterialCoeffiicientEditField.Value = CA;
elseif app.CeilingMaterialDropDown.Value == strcmp(value, 'Fibreglass Rolls 2"')
    CA = 0.90;
    app.CeilingMaterialCoeffiicientEditField.Value = CA;
elseif app.CeilingMaterialDropDown.Value == strcmp(value, 'wood')
    CA = 0.07;
    app.CeilingMaterialCoeffiicientEditField.Value = CA;
elseif app.CeilingMaterialDropDown.Value == strcmp(value, 'Foam Sonex 2"')
    CA = 0.81;
    app.CeilingMaterialCoeffiicientEditField.Value = CA;
elseif app.CeilingMaterialDropDown.Value == strcmp(value, 'Foam SDG 3"')
    CA = 0.91;
    app.CeilingMaterialCoeffiicientEditField.Value = CA;
elseif app.CeilingMaterialDropDown.Value == strcmp(value, 'Foam SDG 4"')
    CA = 0.99;
    app.CeilingMaterialCoeffiicientEditField.Value = CA;
elseif app.CeilingMaterialDropDown.Value == strcmp(value,'Foam Polyur 1"')
    CA = 1.00;
    app.CeilingMaterialCoeffiicientEditField.Value = CA;
elseif app.CeilingMaterialDropDown.Value == strcmp(value, 'Foam Polyur 1/2"')
    CA = 0.60;
    app.CeilingMaterialCoeffiicientEditField.Value = CA;
elseif app.CeilingMaterialDropDown.Value == strcmp(value, 'Plaster smooth on brick')
    CA = 0.03;
    app.CeilingMaterialCoeffiicientEditField.Value = CA;
elseif app.CeilingMaterialDropDown.Value == strcmp(value,'Plaster rough on lath')
    CA = 0.05;
    app.CeilingMaterialCoeffiicientEditField.Value = CA;
elseif app.CeilingMaterialDropDown.Value == strcmp(value,'Sheetrock 1/2"')
    CA = 0.04;
    app.CeilingMaterialCoeffiicientEditField.Value = CA;
elseif app.CeilingMaterialDropDown.Value == strcmp(value, 'wood 3/8"')
    CA = 0.09;
    app.CeilingMaterialCoeffiicientEditField.Value = CA;
elseif app.CeilingMaterialDropDown.Value == strcmp(value,'Hard Surface')
    CA = 0.03;
    app.CeilingMaterialCoeffiicientEditField.Value = CA;
end

% think this may be the problem
app.AreaofAbsorptionSaEditField.Value = (app.FloorEditField.Value + FA) + (app.WallsEditField.Value + WA) + (app.CeilingEditField.Value + CA);  %


c = 0.161;
a = (app.RoomVolumeEditField.Value/app.AreaofAbsorptionSaEditField.Value);
app.RT60EditField.Value = c/a;

Answer 1

[Adam Danz]

Problems:

1. You've got 3 variables named "value" and they all have the same value which is equal to the last of those variables since you're overwriting the first two.

2. Instead of a bunch of if/else, use a switch, case, otherwise. It's much more organized and efficient.

3. strcmp() returns a logical array where true values mark matches. Is that really what's stored in app.FloorMaterialDropDown.Value, a logical value? If so, just use

if app.FloorMaterialDropDown.Value && strcmp(value,'Concrete or Tile')
% or, if you're expecting a non-scalar 
if app.FloorMaterialDropDown.Value & strcmp(value,'Concrete or Tile') 
% but I doubt this is what's stored in the dropdown menu....

4. Usually case sensitivity is not desired. If this is the case for you, use strcmpi() instead of strcmp() so "concrete..." can be matched with "Concrete...".

5. Regarding the comment you left pointing to the line that you think is causing the problem, put a breakpoint at that line in your App code so that execution is paused and evaluate the values of each variable. I think you'll see that the problem is within your conditionals (which should be changed to switch/case).

[Emily Tobin]

Hi, the drop down is not meant to produce a logical value. I basically want the user to be able to select an option of material and depending on what they selected a value will be passed into an equation later on.

Im still having trouble with the variables being unassigned.

thank you for your help so far, greatly appriciated :)

FA = app.FloorMaterialCoefficientEditField.Value;
WA = app.WallMaterialAbsoprtionCoeffecientEditField.Value;
CA = app.CeilingMaterialCoeffiicientEditField.Value;
     
         switch FA
             case app.FloorMaterialDropDown.Value == strcmp(value,'Concrete or Tile')
               FA = 0.02;
              
             case app.FloorMaterialDropDown.Value == strcmp(value,'Linoleum/ Vinyl Floor On Concrete')              
               FA = 0.03; 
               
             case app.FloorMaterialDropDown.Value == strcmp(value,'Wood on Joists')
               FA = 0.07;
              
             case app.FloorMaterialDropDown.Value == strcmp(value,'Parquet on Concrete')

               FA = 0.06; 
        
             case app.FloorMaterialDropDown.Value == strcmp(value,'Carpet on Concrete')

               FA = 0.37; 
              
             case app.FloorMaterialDropDown.Value == strcmp(value,'Carpet on foam')

               FA = 0.69;
              
             otherwise app.FloorMaterialDropDown.Value == strcmp(value,'6mm carpet')
               FA = 0.31;
              
         end 
           switch WA 
               case app.WallMaterialDropDown.Value == strcmp(value,'Brick Unglazed')

               WA = 0.04;
              
               case app.WallMaterialDropDown.Value == strcmp(value,'Sheetrock 1/2"')

               WA = 0.04;
              
               case app.WallMaterialDropDown.Value == strcmp(value,'Wood 3/8 Plywood Panel')

               WA = 0.09;
               
               case app.WallMaterialDropDown.Value == strcmp(value,'Marble and Tile ')

               WA = 0.01;
              
               case app.WallMaterialDropDown.Value == strcmp(value,'Plaster Rough on Lath')
 
               WA = 0.05;
             
               case app.WallMaterialDropDown.Value == strcmp(value,'Plaster Smooth On Brick')
              
               WA = 0.03;
              
               case app.WallMaterialDropDown.Value == strcmp(value,'Glass: Window')
 
               WA = 0.12;

               case app.WallMaterialDropDown.Value == strcmp(value,'Foam: Polyur 1"')

               WA = 1.00;
            
               case app.WallMaterialDropDown.Value == strcmp(value, 'Foam Polyur 1/2"')
   
               WA = 0.60;

               case app.WallMaterialDropDown.Value == strcmp(value, 'Glass 1/4 large plate')
           
               WA = 0.03;
              
               case app.WallMaterialDropDown.Value == strcmp(value, 'Foam SDG 3"')

               WA = 0.91;
           
               case app.WallMaterialDropDown.Value == strcmp(value, 'Foam SDG 4"')

               WA = 0.99;

               case app.WallMaterialDropDown.Value == strcmp(value, 'Fiberglass 5" sprayed')

               WA = 0.70;
              
               case app.WallMaterialDropDown.Value == strcmp(value, 'Fibreglass 2" rolls')
 
               WA = 0.90;
              
               case app.WallMaterialDropDown.Value == strcmp(value, 'Foam Sonex 2"')
 
               WA = 0.81;
              
               case app.WallMaterialDropDown.Value == strcmp(value,'Fiberglass 1" sprayed')
   
               WA = 0.90;

               case app.WallMaterialDropDown.Value == strcmp(value,'Fiberglass ')

               WA = 0.99;
               
               case app.WallMaterialDropDown.Value == strcmp(value,'Curtain 18oz')
  
               WA = 0.72;
               
               case app.WallMaterialDropDown.Value == strcmp(value, 'Fiberglass 2" No gaps')
 
               WA = 0.99;
              
               case app.WallMaterialDropDown.Value == strcmp(value, 'Curtain 14"')

               WA = 0.75;
               
               case app.WallMaterialDropDown.Value == strcmp(value, 'Brick Unglazed and Painted')

               WA = 0.02;
             
               case app.WallMaterialDropDown.Value == strcmp(value, 'Concrete Block Coarse')

               WA = 0.29;
         
               case app.WallMaterialDropDown.Value == strcmp(value, 'Concrete Block Painted')
               WA = 0.07;
             
               case app.WallMaterialDropDown.Value == strcmp(value, 'Curtain 10oz')
               WA = 0.17;
             
               case app.WallMaterialDropDown.Value == strcmp(value, 'Rockwool')
               WA = 0.9; 
              
               otherwise app.WallMaterialDropDown.Value == strcmp(value, 'Hard Surface')
              WA = 0.03;
             
           end
        switch CA 
            case app.CeilingMaterialDropDown.Value == strcmp(value,'Acoustic Tiles')
               CA = 0.56;

            case app.CeilingMaterialDropDown.Value == strcmp(value, 'Acoustic Ceiling Tiles')
               CA = 0.92;
            
            case app.CeilingMaterialDropDown.Value == strcmp(value, 'Fibreglass 2" no airspace')
               CA = 0.99;
            case app.CeilingMaterialDropDown.Value == strcmp(value, 'Fibreglass Spray 5"')
               CA = 0.70;
            case app.CeilingMaterialDropDown.Value == strcmp(value, 'Fibreglass spray 1"')
               CA = 0.90;
            case app.CeilingMaterialDropDown.Value == strcmp(value, 'Fibreglass Rolls 2"')
               CA = 0.90;
            case app.CeilingMaterialDropDown.Value == strcmp(value, 'wood')
               CA = 0.07;
            case app.CeilingMaterialDropDown.Value == strcmp(value, 'Foam Sonex 2"')
               CA = 0.81;
            case app.CeilingMaterialDropDown.Value == strcmp(value, 'Foam SDG 3"')
               CA = 0.91;
            case app.CeilingMaterialDropDown.Value == strcmp(value, 'Foam SDG 4"')
               CA = 0.99;
            case app.CeilingMaterialDropDown.Value == strcmp(value,'Foam Polyur 1"')
               CA = 1.00;
            case app.CeilingMaterialDropDown.Value == strcmp(value, 'Foam Polyur 1/2"')
               CA = 0.60;
            case app.CeilingMaterialDropDown.Value == strcmp(value, 'Plaster smooth on brick')
               CA = 0.03;
            case app.CeilingMaterialDropDown.Value == strcmp(value,'Plaster rough on lath')
               CA = 0.05;
            case app.CeilingMaterialDropDown.Value == strcmp(value,'Sheetrock 1/2"')
               CA = 0.04;
            case app.CeilingMaterialDropDown.Value == strcmp(value, 'wood 3/8"')
               CA = 0.09;
            otherwise app.CeilingMaterialDropDown.Value == strcmp(value,'Hard Surface')
            CA = 0.03;
        end
        
           app.AreaofAbsorptionSaEditField.Value = (app.FloorEditField.Value + FA) + (app.WallsEditField.Value + WA) + (app.CeilingEditField.Value + CA);


           c = 0.161;
           a = (app.RoomVolumeEditField.Value/app.AreaofAbsorptionSaEditField.Value);
           app.RT60EditField.Value = c/a;
        

[Adam Danz]

Please take a few minutes to look through the documentation for strcmp. You're using it incorrectly. Also see the examples on that page.

https://www.mathworks.com/help/matlab/ref/strcmp.html

In fact, you don't need strcmp if you're using a switch/case

FA = app.FloorMaterialCoefficientEditField.Value;
switch FA
    case 'Concrete or Tile'
        FA = 0.02;
        
    case 'Linoleum/ Vinyl Floor On Concrete'
        FA = 0.03;
        
    case 'Wood on Joists'
        FA = 0.07;