@Preben Alsholm hahahaha thank you so much, lack of attention

@Preben Alsholm 

Thank you @Preben Alsholm , about the sys2, do you know why the interval is interpreted as invalid argument?

@tomleslie 

Thank you very much for the answer, helped a lot :)

It is intended to be a(t), this is a parameter of my metric.

I will work on those boundary conditions, then values for m and phi, so it is ok to appear some singularities when calculating.