如何在不使用 Perl 中的矩阵库的情况下对矩阵进行操作？答案

【问题标题】：How can I operate with the matrix without using the matrix library in Perl?如何在不使用 Perl 中的矩阵库的情况下对矩阵进行操作？
【发布时间】：2019-12-10 10:32:02
【问题描述】：

我需要在不使用库的情况下用 Perl 编写一个矩阵。如何在我的代码中实现以下操作？ - 转置矩阵 - 计算每一行和每一列的平均值，（我试图在下面的脚本中制作它） - 找到整个矩阵中的最小值， - 找到值总和最小的行的索引。

我将此代码用于矩阵运算，它可以工作，但我完全不明白如何执行这些运算。提前谢谢你

#!usr/bin/perl 
use strict; 
use warnings; 



my(@MatrixA, @MatrixB, @Resultant) = ((), (), ()); 

# Asking for User Input for Matrix A 
print"Let's begin with the matrix A dimensions\n"; 
print"\tPlease, enter how many rows should Matrix A have:"; 
chomp(my$rowA= <>);  # CHOMP TO TAKE USER INPUT 
print"\tPlease, enter how many columns should Matrix A have:"; 
chomp(my$columnA= <>); 

# Asking for User Input for Matrix B 
print"Then we have matrix B:\n"; 
print"\tPlease, enter how many rows should Matrix B have:"; 
chomp(my$rowB= <>); 
print"\tPlease, enter how many columns should Matrix B have:"; 
chomp(my$columnB= <>); 

# Asking User to input elements of matrices 
if($rowA== $rowB and $columnA== $columnB) #checking the dimensions whether they match
{ 
    print"Enter $rowA * $columnA elements in MatrixA:\n";  
    foreach my $m(0..$rowA- 1) 
    { 
        foreach my $n(0..$columnA- 1) 
        { 
            chomp($MatrixA[$m][$n] = <>);  # reading the values
        } 
    } 

    print"Enter $rowB * $columnB elements in MatrixB:\n";  
    foreach my$m(0..$rowB- 1) 
    { 
        foreach my $n(0..$columnB- 1) 
        { 
            chomp($MatrixB[$m][$n] = <>);  # reading the values 
        } 
    } 

    # Performing Addition operation 
    foreach my $m(0..$rowB- 1) 
    { 
        foreach my $n(0..$columnB- 1) 
        { 
            $Resultant[$m][$n] = $MatrixA[$m][$n] +  
                                 $MatrixB[$m][$n]; 
        } 
    } 

    # Printing Matrix A 
    print"MatrixA is :\n";  
    foreach my $m(0..$rowB- 1) 
    { 
        foreach my $n(0..$columnB- 1) 
        { 
            print"$MatrixA[$m][$n] "; 
        } 
        print"\n"; 
    } 

    # Printing Matrix B 
    print"MatrixB is :\n";  
    foreach my$m(0..$rowB- 1) 
    { 
        foreach my$n(0..$columnB- 1) 
        { 
            print"$MatrixB[$m][$n] "; 
        } 
        print"\n"; 
    } 

    # Printing the sum of Matrices 
    print"SUM of MatrixA and MatrixB is :\n";  
    foreach my $m(0..$rowB- 1) 
    { 
        foreach my $n(0..$columnB- 1) 
        { 
            print"$Resultant[$m][$n] "; 
        } 
        print"\n"; 
    } 

    # Printing the average of Matrices 
    print"The average of Matrices (row) :\n";  
    foreach my $m(0..$rowB- 1) 
    { 
        my $sum_r += $m;
        my $average_r = $sum_r/$rowB;
        print "Average is $average_r\n";
            print"\n";        
    }
    print"The average of Matrices (column) :\n";
    foreach my $n(0..$columnB- 1) 
          { 
        my $sum_c += $n;
        my $average_c = $sum_c/$columnB;
        print "Average is $average_c\n";
            print"\n";
          }     
} 

# Error if Matrices are of different order 
else
{ 
    print"Matrices order does not MATCH, Addition is not Possible"; 
}

【问题讨论】：

如果您对问题的数学方面有疑问，我们对此概不负责。请参考math.stackexchange.com。对于学习 Perl，我推荐Learning Perl, 6th Edition。
你需要弄清楚算法。拿纸和铅笔。写下几个小的示例矩阵。手动计算每列的平均值。注意重复的工作部分。用英语写下重复部分的描述，就好像你想向同事解释一样。现在告诉计算机，使用 Perl。 -- 对其他三个任务做同样的事情。

标签： perl matrix

【解决方案1】：

这是一个如何转置矩阵的示例：

my @MatrixA = ([1,2,3], [4, 5, 6]);
my @MatrixA_T = transpose(@MatrixA);

sub transpose {
    my (@M) = @_;

    my @MT;
    for my $i (0..$#M) {
        for my $j (0..$#{$M[0]}) {
            $MT[$j][$i] = $M[$i][$j];
        }
    }
    return @MT;
}

请注意，如果您使用PDL 模块，则矩阵运算已经实现。

【讨论】：