How do you evaluate a function over a range of more than one variable? Rate-Time Decline Curve Analysis

After a lot of trial and error I am still unable to generate the output I desire in what I believe is the correct and most efficient method in Matlab. I am using Matlab as an alternative to Excel in order to more efficiently calculate and display the data, so I'm hoping to be able to solve this issue with your help. Thanks in advance!

Quite simply, I am trying to calculate the value of "q" given an initial rate "qi", a constant "b", and a decline rate "di" at time t. I have been successful at calculating the function and solving for q over a range of "t" values. by setting t = 0:n. (see formula and code below)

    %Decline curve with b-factor comparison
    % qi = IP rate
    % di = initial decline rate
    % b = B-factor
    % t = time period
    qi=1000; b = 1; di=.012; t=0:14600;
    function q = hbcurve(qi,b,di,t) %define function
    q = qi*(1+b*di*t).^(-1/b); %function forumula

My Problem: I am having difficulty in being able to evaluate the function over a range of t values as mentioned above while simultaneously evaluating the function over b = 1:0.1:2. I've been able to calculate these values but only by manual iteration of the functions. I've scoured this site, manuals, blogs, etc, and tried for loops and pre-allocation to no avail.

My Goal: Evaluate the function over a range of the variable "t" and "b" and output this data to a matrix with dimensions are as long and wide as the "t" and "b" variables. I am trying to avoid achieving my goal with code such as that below.

b1 = hyperdecline(qi,1,di,t); b1cum = cumsum(b1);
b11 = hyperdecline(qi,1.1,di,t); b11cum = cumsum(b11);
b12 = hyperdecline(qi,1.2,di,t); b12cum = cumsum(b12);
b13 = hyperdecline(qi,1.3,di,t); b13cum = cumsum(b13);
b14 = hyperdecline(qi,1.4,di,t); b14cum = cumsum(b14);
b15 = hyperdecline(qi,1.5,di,t); b15cum = cumsum(b15);
b16 = hyperdecline(qi,1.6,di,t); b16cum = cumsum(b16);
b17 = hyperdecline(qi,1.7,di,t); b17cum = cumsum(b17);
b18 = hyperdecline(qi,1.8,di,t); b18cum = cumsum(b18);
b19 = hyperdecline(qi,1.9,di,t); b19cum = cumsum(b19);
b2 = hyperdecline(qi,2,di,t); b2cum = cumsum(b2);

Answer 1

[José-Luis]

t=0:14600;
b = 1:0.1:2;

[T B] = ndgrid(t,b);

Now you can evaluate your function for all values of T and B. You can either loop through all values (that would sort of defeat the point of using ndgrid() though ), or you could rewrite hbcurve() so it accepts array inputs:

 q = qi*(1+B.*di.*T).^(-1./B);

[txvmi07]

Thank you very much, this was extremely helpful. As I expected the answer was simple, I just couldn't get there myself! Thanks again!

[José-Luis]

My pleasure