Question

water volume in the reservoir as a function of time
V(t)=10^9 + 10^8*(1-e^(-t/100)) - r*t
where V is the water volume in liters, t is time in days and r is the town's consumption rate in liters per day. Write 2 user defined functions. The first function should define the function V(t) for use with the fzero function. The second duction should use fzero to compute how long it will take for the water volume to decrease to x percent of its initial value of 10^9 L. The inputs to the second function should be x and r. Test your functions for the case where x = 50 percent and r = 10^7 L/day.

Answer 1

Its a mathlab question, I'm having some trouble it

Answer 2

function f= fun(t)
global r
f=(10^9)+(10^8)*(1-exp(-t/100))-(r*t);

Answer 3

then

Answer 4

global r
r=10^7;
x=50/100;
c2=(-x*(10^9));
c1=10^9;

c0=[c2,c1];
t=fzero('fun',c0)

Answer 5

but then i get

Answer 6

??? Error using ==> fzero at 260
Function values at interval endpoints must be finite and
real.

Error in ==> test at 18
t=fzero('fun',c0)