## Resolve Error: Data Type Mismatch

### Issue

In this example, y uses the default `fimath` setting `FullPrecision` for the `SumMode` property. At each iteration of the for-loop in the function `mysum`, the word length of y grows by one bit.

During simulation in MATLAB®, there is no issue because data types can easily change in MATLAB. However, a data type mismatch error occurs at build time because data types must remain static in C.

### Possible Solutions

Rewrite the function to use subscripted assignment within the for-loop.

In this example, rewrite y = y + x(n) as y(:) = y + x(n), so that the value on the right is assigned in to the data type of y. This assignment preserves the `numerictype` of y and avoids the type mismatch error.

Original AlgorithmNew Algorithm

Function:

```function y = mysum(x,T) %#codegen y = zeros(size(x), 'like', T.y); for n = 1:length(x) y = y + x(n); end end```

Function:

```function y = mysum(x,T) %#codegen y = zeros(size(x), 'like', T.y); for n = 1:length(x) y(:) = y + x(n); end end```

Types Table:

```function T = mytypes(dt) switch(dt) case 'fixed' F = fimath('RoundingMethod', 'Floor') T.x = fi([],1,16,11, F); T.y = fi([],1,16,6, F); end end```

Types Table:

```function T = mytypes(dt) switch(dt) case 'fixed' F = fimath('RoundingMethod', 'Floor') T.x = fi([],1,16,11, F); T.y = fi([],1,16,6, F); end end```