从行优先顺序的数组创建本征矩阵 [英] Creating an Eigen matrix from an array with row-major order

问题描述

我有一个双精度数组，我想使用Eigen库创建一个4×4矩阵.我还想指定数据以行优先顺序存储.我该怎么办?

I have an array of doubles, and I want to create a 4-by-4 matrix using the Eigen library. I also want to specify that the data is stored in row-major order. How can I do this?

我尝试了以下操作，但无法编译:

I have tried the following, but it does not compile:

double data[16];
Eigen::Matrix4d M = Eigen::Map<Eigen::Matrix4d>(data, 4, 4, Eigen::RowMajor);

推荐答案

您需要将行主要矩阵类型传递给Map，例如:

You need to pass a row-major matrix type to Map, e.g.:

Map<Matrix<double,4,4,RowMajor> > M(data);

然后您可以将M用作特征矩阵，数据值将被修改，例如:

then you can use M as an Eigen matrix, and the values of data will be modified, e.g.:

M = M.inverse();

如果要将数据复制到真正的以列为主的本征矩阵，请执行以下操作:

If you want to copy the data to a true column-major Eigen matrix, then do:

Matrix4d M = Map<Matrix<double,4,4,RowMajor> >(data);

当然，您也可以使用M的正确类型将其复制到以行为主的矩阵.

Of course, you can also copy to a row-major matrix by using the right type for M.

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