Dear Gretl Team,

Today I've found a very strange problem on Gretl. Please take a look at the following hansl code:

<hansl>

open hamilton.gdt

 

series x = PC6IT

series y = PZUNEW

series z = EXRITL

 

series teste = ((x[1989:01]/y[1989:01]) * z)/z * 100

 

diff teste

 

gnuplot teste d_teste --time-series --with-lines --output=display

</hansel>


I think that mathematically the "teste" expression is a constant. So, the first difference of a constant variable is equal to zero.


Am I missing something?


Um abraço,

Henrique Coêlho de Andrade