Inconsistent Performance by MATLAB 2010b

Hi All (specially MATLAB developers)

I run the following code

for k=1:783
sortedfile=sortrows(tosort,k,'descend');
ranks(:,k)=sortedfile(:,1);
end;

it runs once very smoothly and produces a dataset array "ranks". Next time I run the same code, it gives the following error first

the following error occurred converting from dataset to double:
Error using ==> double
Conversion to double from cell is not possible.

also when I start my loop from 2:783 (bcoz first column contains asset names,I receive the following error:

??? Index exceeds matrix dimensions.

Also exporting 783 columns to XLS file is not allowed, when I write:

export(ranks,'XLSfile','rankfile2.xlsx');

it writes upto column 680 and returns and error number:

Error writing dataset variable 'Var690' to 'rankfile2.xlsx':
Excel returned: Error: Object returned error code: 0x800A03EC..

MATLAB gurus, plz reply....how to tackle with this.

Regards,

AMD.

[Jan]

Currently the question is not clear. What is the type of "tosort"? What does "next time I run the same code" mean: inside the same function, or calling the same function again, or with the same data? Did you pre-allocate the variable ranks? If so, to which type and dimensions?