' - - File: XVIf   BVP with multiple solutions.  Found using roots graph.

' Given: X"(t) + Abs[X{t}] = 0
 
F{t,x,y} = y
G{t,x,y} = -Abs[x]

to = 0: xo = 0 : tb = 4: xb = -2 : n = 200 : a1 = -0.07 :  a2 = 2

BVP[F, G, {to,xo,tb,xb} { a1; a2 } {1, .01, 2}]

' Suggested Setup:
'   1. Set a1 = - number, say -3;  a2 = + number, try 5 as a guess. Do a roots plot.
'   2. From the roots plot, pick two ranges to find the precise crossing. (Use 0 in last column).
'       a. One range lies about two, when you display its slope.
'       b. Carefully, note that another root lies around -2 to the origin. Pick a1 & a2 
'           to cover this range. Display and write down the slope.
'   3. The values for a1 & a2 are used above in BVP that results in two plots.

' Other solutions?


