The leastsq function poorly documents the mem option.
Reported by Michael BAUDIN
Originally assigned to Sylvestre LEDRU
The help page indicates :
mem: [...] Default value is around 6.
"around" means nothing and should be removed.
The optim help page indicates:
mem : [...] Default value is 10.
Then we can guess that the default value of mem is also 10 for leastsq.