Octave can solve sets of nonlinear equations of the form
F (x) = 0
using the function
fsolve, which is based on the MINPACK
f (x)and an initial starting point x0,
fsolvesolves the set of equations such that
f(x) == 0.
fsolve. Given one argument,
fsolve_optionsreturns the value of the corresponding option. If no arguments are supplied, the names of all the available options and their current values are displayed.
Here is a complete example. To solve the set of equations
-2x^2 + 3xy + 4 sin(y) = 6 3x^2 - 2xy^2 + 3 cos(x) = -4
you first need to write a function to compute the value of the given function. For example:
function y = f (x) y(1) = -2*x(1)^2 + 3*x(1)*x(2) + 4*sin(x(2)) - 6; y(2) = 3*x(1)^2 - 2*x(1)*x(2)^2 + 3*cos(x(1)) + 4; endfunction
fsolve with a specified initial condition to find the
roots of the system of equations. For example, given the function
f defined above,
[x, info] = fsolve ("f", [1; 2])
results in the solution
x = 0.57983 2.54621 info = 1
A value of
info = 1 indicates that the solution has converged.
perror may be used to print English messages
corresponding to the numeric error codes. For example,
perror ("fsolve", 1) -| solution converged to requested tolerance
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