Finding all possible zeros for a function with 2 independent variables.

I have the following function where v & n are the independent variables and the others are constants. am(v) and bm(v) are two other separate functions of v.
function f = F(v,n,i,a,b,vNa,vK,vL)
amv = am(v);
bmv = bm(v);
tmv = 1./(amv + bmv);
f = i - 120.*(amv.*tmv).^3.*(b-a.*n).*(v-vNa) - 36.*(n).^4.*(v-vK)-0.3.*(v-vL);
end
I basically want to find the values of v & n where f = 0. I just don't really know where to start when I have two unknowns. I've tried looking at https://www.mathworks.com/help/optim/ug/fsolve.html but it did not make much sense.
The end goal is to graph the values of v and n on a plot, so having it result in a matrix would be useful. I am not sure if that's possible though. Thank you for any help in advance!

 采纳的回答

The contour and fimplicit funcitons are likely best for this.
For contour, create a matrix for ‘v’ and ‘n’ using either ndgrid or meshgrid, then specify [0 0] as the contour to plot:
NM = number_of_elements;
vv = linspace(minvalv, maxvalv, N);
nv = linspace(minvaln, maxvaln, N);
[Vm,Nm] = ndgrid(vv, nv);
Fm = F(vv,nv,,i,a,b,vNa,vK,vL);
figure
C = contour(Vm,Nm,Fm, [0 0])
That will plot them. To retrieve the (x,y) values, use find to determine the locations of ‘C(1,:)’ that equal zero, then ‘C(2,:)’ of those indices are the number of (x,y) pairs in the contour. That will determine how to recover them.
It will likely be easier to plot and recover the data from the fimplicit plot.
.

2 个评论

I replaced ndgrid with meshgrid, and used Vm and Nm for the function call and it worked. Thank you so much!

请先登录,再进行评论。

更多回答(0 个)

类别

帮助中心File Exchange 中查找有关 Logical 的更多信息

产品

版本

R2022a

标签

Community Treasure Hunt

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

Start Hunting!

Translated by