In simple ACO

[nguyenviettien13]

Can you explain for me why was the code block added ?
for (from = 0; from < MAX_CITIES; from++)
{
for (to = 0; to<MAX_CITIES; to++)
{
phero[from][to] *= RHO;
}
}
I think RHO is Evaporation rate and computed in line: 264
phero[from][to] *= (1.0 - RHO);