Question

如何编写具有3个输入的函数（2个矢量，包括系数[abc]和x值的矢量），形式为ax + by = c的两个线方程，输出给出该点的x和y值的向量交集。

示例：solveSystem（[1 -1 -1]，[3 1 9]， - 5：5）应该产生[2 3]

到目前为止：

function coeff=fitPoly(mat)

% this function takes as an input an nx2 matrix consisting of the
% coordinates of n points in the xy-plane and give as an output the unique
% polynomial (of degree <= n-1) passing through those points.


[n,m]=size(mat);  % n=the number of rows=the number of points
% build the matrix C
if m~=2
    fprintf('Error: incorrect input');
    coeff=0;
  else
  C=mat(:,2);  % c is the vector of y-coordinates which is the 2nd column of mat

  % build the matrix A
  for i=1:n
    for j=1:n
        A(i,j)=(mat(i,1))^(n-j);
    end
end
coeff=inv(A)*C;
end

Answer 1

你不需要向量x来求解两条线的交集：

function xy = solve(c1,c2)
  A = [c1(1:2); c2(1:2)];
  b = [c1(3); c2(3)];
  xy = A\b;
end

将为

计算

xy = solve([1 -1 -1],[3 1 9])

矩阵

A = [1 -1;
     3 1]
b = [-1
     9]

这样

xy = A^-1 b = [2
               3]

Matlab：输出向量给出交叉点的x和y值

1 个答案: