System of nonlinear equations

I have designed a code for a system of two nonlinear equation (code given). I have tried 'fsolve' to find the solutions. But I am getting the 'No Solution found' message. Can anyone please let me know how to fix it or what approach should I take to solve this set of equation? Thanks

clear all, close all,  clc
gs  = [10e12 99e15];
[N,fval,exit,output] = fsolve(@Density,gs);
N
fval
Density(gs)
exit
output
 function nNonlin = Density (z)
 Ns0 = z(1);
 Nt0 = z(2);
 k_rs = 3.2e7;
 k_ISC = 3.1e7;
 k_RISC = 5.6e3;
 k_ST = 2e-11;
 k_TT = 5e-15;
 k_NRT = 8.2e2;
 J = 0.1;
 d = 15e-7;
 e = 1.6e-19;
 nNonlin(1) = -(k_rs+k_ISC)*Ns0+k_RISC*Nt0-k_ST*Ns0*Nt0+0.25*k_TT*Nt0.^2+J/(4*d*e);
 nNonlin(2) = k_ISC*Ns0-(k_RISC+k_NRT)*Nt0-1.25*k_TT*Nt0.^2+(3*J)/(4*d*e);
end
 

Answer 1

[Walter Roberson]

The equation is a cubic. In all three solutions, z(1) is complex valued. In two of the three solutions, z(2) is real-valued, and in the third it is complex-valued.

fsolve() in earlier releases could only handle real-valued equations; even in later releases it can fail on complex-valued equations.

[Monirul Hasan]

Hi Walter, I have tried to use some random small numbers instead of the large experimental values, in that case it was able give solutions. Just wondering is there a way to fix it? By the way I didn't understand the part the equation being cubic. Thanks.