@tomleslie 

FYI if you are interested your DD[i,1] should have said DD[j,1] that's where your "fault" was. My numbers are correct now.

i can't thank you enough for this. Helped me out alot. People like you are the real MVP.

It's a little easier for me to see if i have the results in Inches and bar but ill manage that myself i hope. Thanks agian, and have a great day!

@tomleslie 

THANKS ALOT. Exactly how i wanted it, only the results are a little off i think. Just one more thing and i'll be out of you hair :)

Is it possible to plot or maybe even 3D plot the results like i did i this attached excel document .Pressure_loss_pipes.xlsx

Pressure_loss_in_pipes_1.mw

Okay the first worksheet i made was this. This is the actualy number i want!!! But the way i did it is horrible. How do i make this nice using matix.

What i want my equation to say is the first data point in my matrix should be

(rho*v(1,1)*DD(1,1))/mu moving to the right i want the next data point in my matrix to be (rho*v(1,2*DD(2,1))/mu and so on. 

@tomleslie 

I see i gives a nice fine matrix. But what about my next equation, then my 5*9 matrix needs to be muliplyed to my DD which is a vector. This gives me problems getting the right numbers.

@Carl Love 

Hey Car Love, thanks for the new method you gave me. I created the matrix as so

v:=Matrix((5,9),(i,j)->combine(V__dot[i]/A[j],'units')); and it gives me a perfect matrix, thanks.

But my next problem comes when i need this eqation. Rey:=(rho*v*DD)/mu how do i create this matrix so i get the 45 new data points? i've tried and i get too many my suggestion would be

Rey:=Matrix((5,9),(i,j)->combine((rho*v*DD)[i]/mu[j])); But this dosent work.. do you notice what i'm doing wrong?

@tomleslie 

Hey Tom,

Thanks for the reply. I considered creating a 9*5 matrix but i just wanted the layout to be smooth and i would have alot of "zero's" in that matrix. All i wanted to figure out was if my way was possible, else i would use the matrix method.

If it makes sense i'm trying to end up with a 3D plot of the pressure losses of diffrent diameters (DD) and different volumeflows (V__dot) in three diffrent lenghts of hoses (L1..L3). As you can see that gives alot of data.

But thanks agian, i think i'll try the matrix method instead.