fsolve on polynominal function
显示 更早的评论
Hey!
I need to use fsolve to calculate y=1 in a non linear function, y = ax^2 + bx + c .
x, a, b and c is matrix.
I don't understand the documentation around fsolve and need this to work by the end of the day..
If anybody can help out, I would be so happy!
The code I have been trying out, is below. Ask if there is anything I can help with!
x0 = [0,0];
solveTest = fsolve(myFun(x, a, b, c), x0);
function y = myFun(x, a, b, c)
y = a.*x.^2 + b.*x + c;
y(x) = 1;
end
回答（1 个）
Guillaume
2019-9-27
roots([a, b, c-1])
your myfun doesn't make much sense:
y = a.*x.^2 + b.*x + c; %assuming a,b,c and x are scalar results in y being a scalar value
y(x) = 1; %set the element of array y (which has just one element) at index x (which may not even be integer) to 1
fsolve solves for 
not for 
. Again, the latter is easily rewrittent as 
but using fsolve, an iterative process that may return an approximation of the roots is a complete waste of time when there's a function for getting the roots of polynomial.
not for . Again, the latter is easily rewrittent as but using fsolve, an iterative process that may return an approximation of the roots is a complete waste of time when there's a function for getting the roots of polynomial.类别
在 帮助中心 和 File Exchange 中查找有关 Linear Algebra 的更多信息
2019-9-27
2019-9-27
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
