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# How to resolve "Conversion to double from cell is not possible."

Asked by James Carter on 1 May 2013

Can someone point out what I am doing wrong. If I use the internals of the following function in command-line, the code works fine, but when I attempt to execute through the function, I get the error listed above listed for line 12. The offending code is: NewArry(3:LenB+2) = varargin;

`    function [maxVal, maxInd] = inner_product(varargin)`
```    % varargin contains the accumulated signal returns
K = [2 3 10 2 1];
LenB = length(varargin);
EndL = varargin(1);
EndR = varargin(LenB);
%Pre-allocate New Array
NewArry = zeros(1,LenB + 4);
NewArry(3:LenB+2) = varargin;
NewArry(1) = EndL;
NewArry(2) = EndL;
NewArry(LenB + 3) = EndR;
NewArry(LenB + 4) = EndR;
FinalArry = zeros(1:LenB); %Preallocate array to hold inner product values```
```    for x = 1:LenB
%Take the first group of 5 from the NewArray
Y = NewArry(x:x+4);
%Take The Inner Product of this with the Kernel
IP = Y * K';
%Store this value
FinalArry(1,x) = IP;
end```
`    [maxVal, maxInd] = max(FinalArry);`
`    end `

When I assign varargin, and then pass it to the function, [maxVal, maxInd] = inner_product(varargin) it fails.

Thanks

## Products

Answer by Walter Roberson on 1 May 2013

varargin is a cell array, and you cannot assign a cell array to a numeric array. Look again at your statements

```NewArry = zeros(1,LenB + 4);
NewArry(3:LenB+2) = varargin;
```

James Carter on 1 May 2013

varargin is a 1 x 1021 vector, not a cell array, so I am not sure where it is picking up that classification. Besides, why does this work when I run the bare code outside the function but then only triggers the error when I run the exact same code within the function? Attempting to use the cell2mat routine then results in a dimensional mismatch.

Thanks

JC

Walter Roberson on 1 May 2013

No, varargin{1} might be a 1 x 1021 vector, but varargin will always be a cell array.

Outside of a function, varargin references the script that is just the help information for varargin, and would present an error if used in a context that requires a value. varargin inside a function is special.

```foo = @(varargin) class(varargin)
```

now try

```foo([1 2 3])
```

and

```foo('hello', 83)
```

and notice that each time the result is "cell".

Answer by Babak on 1 May 2013

use

` cell2mat()`