index out of bounds

hi guys, new to matlab and came across a simple problem that takes me forever to get over. please help.

if rgb(1)==1
  if rgb(2)==1
      if rgb(3)==1
          color='white'; 
      else 
          color='yellow';  
      end
  else
      if rgb(3)==1
      color='magenta';
      else
      color='red';
      end
  end

 else
    if rgb(1)==1
        if rgb(3)==1
            color='cyan';
        else
            color='green';
        end
    else
        if rgb(3)==1
        color='blue';
        else
        color='invalid input';
        end
    end
end

so its pretty much just mix three primary colors as input and output the mixed color.. i have a hard time going through this and i don't know where i did wrong.. thanks for answering. oh and here's the error:

Attempted to access rgb(3); index out of bounds because numel(rgb)=1.

Error in rgb_color (line 26) if rgb(3)==1

Answer 1

[Ilham Hardy]

What is your rgb value?

The error message is very clear. it stated that you tried to access the third index of rgb, whilst rgb only contains one value ( numel(rgb)=1).

Btw, you can also use logical operator instead of nested if-else statement

[Ilham Hardy]

What I meant is what do you get when you type

rgb

in your command window?

Are you sure that your rgb contains three elements? 1x3 matrix?

[Stephen23]

@dingi duan: Ilham Hardy asked you a very simple but important question, because the answer to that question will help us to tell you what is wrong with your code. Here is the question again:

what do you get when you type

rgb

in your command window? (and press enter)

[dingyi duan]

it says" Undefined function or variable 'rgb'."....

[Walter Roberson]

How are you invoking your code? I can see your file is named rgb_color.m but how are you starting it running?

[dingyi duan]

alright guys.. i just found out whats wrong: its my input.. this code is fine.. thanks all for helping.

Answer 2

[Stephen23]

If you want to look up colornames then use my FEX submission colornames:

http://www.mathworks.com/matlabcentral/fileexchange/48155-convert-between-rgb-and-colornames

It is very simple to use:

>> colornames('html',[0.4,0.1,0.6]) 
ans = 'Purple'
>> colornames('html',[0.8,0.9,0.3]) 
ans = 'Yellow'
>> colornames('html',[1,1,1]) 
ans = 'White'

[dingyi duan]

thx but sry i have to use nested if...