hi

Sav  0.225  0.30    0.35  0.40    0.45     0.475 
Qi  0.251  0.90  2.02  3.63  7.2   9.800

If I have to find Fraction flow "Fo"=dSav/dQi the answer are

Fo 0.1127 0.0525 0.038 0.025 0.0112 0.00778

How can I get the answer?

[laurie]

sorry i feel stupid but how can you get 55columns in Fo if you are using dSav =(Sav(n)-Sav(n-1)) and dQi =(Qi(n)-Qi(n-1))? should it be 5 colums instead ?

then you can use something like Fo=dSav ./ dQi (adding . before an operator allows you to make that operation element by element in vectors)

Answer 1

[Thomas]

Sav=[0.225  0.3   0.35   0.4 0.45 0.475 ]
Qi=[0.251  0.90  2.02  3.63  7.2   9.8 ]
Fo=diff(Sav)./diff(Qi)

you can only get 5 values in Fo since you are taking the difference between adjacent values ,. output will have n-1 values..

[abdulhadi khalifa]

I could not get the same answer "0.1127 0.0525 0.038 0.025 0.0112 0.00778 " I got this "0.1156 0.0446 0.0311 0.0140 0.0096"for me I do not need the solution for first point

[Thomas]

Then your data set is not necessarily the same ( you might have more digits of precision, though that should not change the answer too much..). MATLAB cannot give different solutions with the same date and same code (unless you have a random number generator in between changing random seeds..)