Coupled Equations Using ODE45

Hii Friends,

I have the following system of equations to be solved by ODE45. The tspan of Z is from 0-3. The

inital conditions of B1, b2 and B3 are 0.1,0 and 1 respectively.

I need to plot two cases

1) delk(in the exponential part)=0 which i successfully did.

2) delk does not equal zero but is defined as shown.

How can i plot abs(B1) Vs delk for this case.

Awaiting your advise.

Pavan