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## ODE solve help : predefine a function

Hi,

It would be super great to have any suggestions for the mathcad file I have attached.. Please check the file, I have described it there..

Thanks!

17 REPLIES 17

## Re: ODE solve help : predefine a function

Not sure if I understand correctly what you want to achieve,

I wonder why you would want to introduce a third unknown function in the solve block which is dependent in a simple way on the function N.p which you are solving for.

Are you looking for something like this:

How about this??

## Re: ODE solve help : predefine a function

I guess the initial value of M.p should not be 1 but 30 ((1-delta2)*P.N.)

But I wonder why the result is so much different!?

EDIT: I felt into the same trapdoor. It should rather be like this:

## Re: ODE solve help : predefine a function

Hi,

I think it is getting a bit deviated from i want to achieve.. I don't want to add an extra M.p on the ODE block, I am only trying to simplify my equations.

What i trying to achieve is to make the C.p(t) equation look a bit simple by shrinking ((1-delta2)*P.N' N.p(t)) into one variable such as M.p(t).

such as to predefine a variable,

M.p(t) = (1-delta).P.N*N.p(t)

So that,

C.p(t) = M.p(t) - µ.pCp(t)

or if this is possible?

## Re: ODE solve help : predefine a function

i think the picture is not attached well.. I cannot see it..

## Re: ODE solve help : predefine a function

 preeti baskaran wrote:i think the picture is not attached well.. I cannot see it..

This unfortunately happens ever so often.

Hope it works this time:

## Re: ODE solve help : predefine a function

Look at Fred's post and the picture I just posted a second time.

Or maybe the second pic in my first replay, if you still want to solve for N.p and not M.p.

## Re: ODE solve help : predefine a function

But.. did u read the post that i replied recently?

I wonder why you would want to introduce a third unknown function in the solve block which is dependent in a simple way on the function N.p which you are solving for.

Are you looking for something like this:

I dont want to introduce a third unknown function, I would just like to simplify my equations by predefining them

## Re: ODE solve help : predefine a function

Go read the sheet I posted.

You can do a simple modification of your solve block allows M (t) instead of N (t). There is some question about boundary conditions.

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