C ++特征库：将行向量中的元素与向量进行互斥

Question

I am trying to obtain a matrix consisting of the product between a vector and respective elements from a row vector like this:

Eigen::Vector3f vec;
vec << 1,
       2,
       3;

Eigen::RowVectorXf val;
val.setLinSpaced(5, 1, 5); //val = [1,2,3,4,5]

//result should be
//1,2,3,4,5
//2,4,6,8,10
//3,6,9,12,15

After seeing this question , I have tried

val.array().colwise()*vec.array()

and

vec.array().rowwise()*val.array()

but they just don't work.

val is a 1xn vector.

Answer 1

您需要标准矩阵产品：

MatrixXf res = vec * val;