Isso define o comprimento da unidade de ambos os eixos para o mesmo valor:
set size ratio -1
Aqui está um trecho da documentação:
set size ratio <r>
...The meaning of a negative value for
<r>
is different. If<r>=-1
, gnuplot tries to set the scales so that the unit has the same length on both the x and y axes. This is equivalent toset view equal xy
. See set view equal. If<r>=-2
, the unit on y has twice the length of the unit on x, and so on.