快速搭建一个网站,php做的网站代码,网上购物网站大全,成都广告公司黑蚁1. 块操作 块是matrix或array中的矩形子部分。
2. 使用块 函数.block()#xff0c;有两种形式 operation 构建一个动态尺寸的block 构建一个固定尺寸的block 起点(i,j)块大小(p,q) .block(i,j,p,q) .block p,q (i,j) Eigen中#xff0c;索引从0开始。 两个版本…1. 块操作 块是matrix或array中的矩形子部分。
2. 使用块 函数.block()有两种形式 operation 构建一个动态尺寸的block 构建一个固定尺寸的block 起点(i,j)块大小(p,q) .block(i,j,p,q) .block p,q (i,j) Eigen中索引从0开始。 两个版本都可以用于固定尺寸和动态尺寸的matrix/array。功能是等价的只是固定尺寸的版本在block较小时速度更快一些。
int main(){Eigen::MatrixXf m(4,4);m 1, 2, 3, 4,5, 6, 7, 8,9,10,11,12,13,14,15,16;cout Block in the middle endl;cout m.block2,2(1,1) endl endl;for (int i 1; i 3; i){cout Block of size i x i endl;cout m.block(0,0,i,i) endl endl;}}
输出
Block in the middle 6 7
10 11 Block of size 1x1
1 Block of size 2x2
1 2
5 6 Block of size 3x3 1 2 3 5 6 7 9 10 11
作为左值
int main(){Array22f m;m 1,2,3,4;Array44f a Array44f::Constant(0.6);cout Here is the array a: endl a endl endl;a.block2,2(1,1) m;cout Here is now a with m copied into its central 2x2 block: endl a endl endl;a.block(0,0,2,3) a.block(2,1,2,3);cout Here is now a with bottom-right 2x3 block copied into top-left 2x2 block: endl a endl endl;}
输出
Here is the array a:
0.6 0.6 0.6 0.6
0.6 0.6 0.6 0.6
0.6 0.6 0.6 0.6
0.6 0.6 0.6 0.6 Here is now a with m copied into its central 2x2 block:
0.6 0.6 0.6 0.6
0.6 1 2 0.6
0.6 3 4 0.6
0.6 0.6 0.6 0.6 Here is now a with bottom-right 2x3 block copied into top-left 2x2 block: 3 4 0.6 0.6
0.6 0.6 0.6 0.6
0.6 3 4 0.6
0.6 0.6 0.6 0.6
3. 行和列 Operation Method ith row matrix.row(i) jth colum matrix.col(j)
int main(){Eigen::MatrixXf m(3,3);m 1,2,3,4,5,6,7,8,9;cout Here is the matrix m: endl m endl;cout 2nd Row: m.row(1) endl;m.col(2) 3 * m.col(0);cout After adding 3 times the first column into the third column, the matrix m is:\n;cout m endl;}
输出
Here is the matrix m:
1 2 3
4 5 6
7 8 9
2nd Row: 4 5 6
After adding 3 times the first column into the third column, the matrix m is: 1 2 6 4 5 18 7 8 30
4. 角相关操作 operation dynamic-size block fixed-size block 左上角p\*q matrix.topLeftCorner(p,q); matrix.topLeftCorner p,q (); 左下角p\*q matrix.bottomLeftCorner(p,q); matrix.bottomLeftCorner p,q (); 右上角p\*q matrix.topRightCorner(p,q); matrix.topRightCorner p,q (); 右下角p\*q matrix.bottomRightCorner(p,q); matrix.bottomRightCorner p,q (); 前q行 matrix.topRows(q); matrix.topRows q (); 后q行 matrix.bottomRows(q); matrix.bottomRows q (); 左p列 matrix.leftCols(p); matrix.leftCols p (); 右p列 matrix.rightCols(p); matrix.rightCols p ();
int main(){Eigen::Matrix4f m;m 1, 2, 3, 4,5, 6, 7, 8,9, 10,11,12,13,14,15,16;cout m.leftCols(2) endl m.leftCols(2) endl endl;cout m.bottomRows2() endl m.bottomRows2() endl endl;m.topLeftCorner(1,3) m.bottomRightCorner(3,1).transpose();cout After assignment, m endl m endl;}
输出
m.leftCols(2) 1 2 5 6 9 10
13 14 m.bottomRows2() 9 10 11 12
13 14 15 16 After assignment, m 8 12 16 4 5 6 7 8 9 10 11 12
13 14 15 16
5. vectors的块操作 operation dynamic-size block fixed-size block 前n个 vector.head(n); vector.head n (); 后n个 vector.tail(n); vector.tail n (); i起始的n个元素 vector.segment(i,n); vector.segment n (i);
