Scaling an array by a certain number so that the area under the curve equals a fixed number

Hi friends,

Say if I have an array Pyy consisting of 1000 elements. I want the area under the curve (x, Pyy) of this array to equal a fixed number, lets call this number 30.

I would like to do this by scaling the Pyy term to create a NEW vector (PyyNEW) (scaled from Pyy) which fits this criteria, so:

trapz(x, PyyNEW) = 30

How do I achieve this? SO far I have this code but doesnt seem to work:

syms a; %create a variable to solve algebraically

for i = 1:1000;

PyyNEW(i,1) = pyy(i,1)*a;

end

eqn = trapz(x, PyyNEW, 1) == 30;

sola = solve(eqn, a);

Answer 1

[David Goodmanson]

HI Christina,

A = trapz(x,pyy) % find the unscaled area

pyy_new = pyy*(30/A);

trapz(x,pyy_new) % this will equal 30