本征：从向量中减去标量 [英] eigen: Subtracting a scalar from a vector

问题描述

使用Eigen库时出现错误，我要做的就是从Eigen :: VectorXf中减去标量。因此，我的代码如下：

I am having an error when using the Eigen library and all I am trying to do is subtract a scalar from an Eigen::VectorXf. So, my code is something as follows:

#define VECTOR_TYPE Eigen::VectorXf
#define MATRIX_TYPE Eigen::MatrixXf

// myMat is of MATRIX_TYPE
JacobiSVD<MATRIX_TYPE> jacobi_svd(myMat,ComputeThinU | ComputeThinV); 

const float offset = 3.0f;
VECTOR_TYPE singular_values = jacobi_svd.singularValues();

VECTOR_TYPE test = singular_values - offset;

最后一行导致编译错误为：

The last line results in a compilation error as:

错误：对二进制表达式无效的操作数（'Eigen :: VectorXf'（又名
'Matrix'）和'float'）
VECTOR_TYPE test =奇异值-比例;

error: invalid operands to binary expression ('Eigen::VectorXf' (aka 'Matrix') and 'float') VECTOR_TYPE test = singular_values - scale;

Eigen / src / Core /../ plugins / CommonCwiseBinaryOps.h：19：28：注意：
候选模板已忽略：与$ b不匹配$ b'MatrixBase'与'float'
EIGEN_MAKE_CWISE_BINARY_OP（operator-，internal :: scalar_difference_op）

Eigen/src/Core/../plugins/CommonCwiseBinaryOps.h:19:28: note: candidate template ignored: could not match 'MatrixBase' against 'float' EIGEN_MAKE_CWISE_BINARY_OP(operator-,internal::scalar_difference_op)

推荐答案

最简单的方法是转到所谓的 array 世界：

The simplest is to move to the so called "array" world:

VECTOR_TYPE test = singular_values.array() - offset;

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