geofísica magneto-exponencial

B( d_{t}[x]·t , d_{t}[y]·t , d_{t}[z]·t ) = (-1)·qk·< ...
... ( (e^{ln(a)·(d_{t}[x]·t)}+(-1))/(d_{t}[x]·t) ) , ...
... ( (e^{ln(a)·(d_{t}[y]·t)}+(-1))/(d_{t}[y]·t) ) , ...
... ( (e^{ln(a)·(d_{t}[z]·t)}+(-1))/(d_{t}[z]·t) ) >


B(0,0,0) = qk·< ln(a) , ln(a) , ln(a) >