Is it possible to solve the below using ode45? Please anyone reply as I am stuck on this for a long time.

Set of five coupled 1st order differential equations (dPi/dz), one each for P1,P2,P3,P4,P5. For conditions, I have values at z=0 for P1,P2,P3 and at z=80 for P4,P5.

How can we do this a BVP as this is a first order system and with unknown boundary values for P1 to P5 at both z=0 and z=80?

Elseif ode45 is the way, then how to convey that the initial conditions for P4 and P5 are at z=80 unlike P1,P2,P3?

Already asked this earlier but still faced problem upon implementing the suggestion given and so want to clarify properly now....

[Torsten]

This is a boundary value problem. Instead of ode45, use bvp4c.

[Jaya]

You mean bvp4c still work even if I supply just P1 to P3 values at z=0 alone and P4,P5 for z=80 alone? Like each differential equation has only one condition.

I mean: for P1 equation i.e. dP1/dz it will have only z=0 condition but not z=80. Similarly, for P4 equation i.e. dP4/dz I have only one condition which is at z=80 and I don't know it at z=0.

Because ALL the BVP problems I saw have conditions defined for each equation at both ends, that's why I am asking this.

[Torsten]

You need a total of 5 conditions. It does not matter how they are distributed on the left and on the right endpoint of the interval. So theoretically no problem for your case to use bvp4c.