**A numerical procedure for finding t.**

My little home computer would run out of memory before this would work with Maple V, release 5.1.

To find the time for the center to be 140, we could ask Maple to solve the following equation for t. This computation may overflow your machine.

`> `
**digits:=4;
fsolve(u(t,0,3/4)+550=140,t,12.9..13);**

`> `
**digits:=10;**

`> `