# How to solve for gamma

4 views (last 30 days)
smith on 2 Dec 2022
Commented: smith on 5 Dec 2022
Hello, I'm trying to solve for gamma in this equation, I was hoping if someone can help out. considering everything else is a constant that can be put as an input.
##### 2 CommentsShowHide 1 older comment
smith on 2 Dec 2022
Hello, I tried but It's not solving.
clc
clear all
dbs=5.3e-10;
das=1.01e-9;
cb=4e3;
ca=1e3;
x0 =0;
x = fsolve(@myfun,x0)
function F = myfun(x)
F = (1-erf(sqrt(x/dbs)))-(((cb/ca)*sqrt(dbs/das))*(erf(sqrt(x/das)))*(exp((x/das)-(x/dbs))));
end

Torsten on 2 Dec 2022
Edited: Torsten on 2 Dec 2022
format long
dbs=5.3e-10;
das=1.01e-9;
cb=4e3;
ca=1e3;
x0 =0;
options = optimset('TolX',1e-14,'TolFun',1e-14);
x = fsolve(@(x)myfun(x,dbs,das,cb,ca),x0,options)
Equation solved. fsolve completed because the vector of function values is near zero as measured by the value of the function tolerance, and the problem appears regular as measured by the gradient.
x =
2.980227787591144e-08
myfun(x,dbs,das,cb,ca)
ans =
-7.180679523372318e-12
function F = myfun(x,dbs,das,cb,ca)
F = (1-erf(sqrt(x/dbs)))-(((cb/ca)*sqrt(dbs/das))*(erf(sqrt(x/das)))*(exp((x/das)-(x/dbs))));
end
smith on 5 Dec 2022
Thank you @Torsten!

### Categories

Find more on Oil, Gas & Petrochemical in Help Center and File Exchange

R2018b

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!