Difference between revisions of "Addition of matrices"

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Requirement for the addition of two matrices is, that they have the same number of rows and the same number of colums. So both matrices have to be an m-by-n matrix. The addition is made by adding each the components:<br/><br/>
 
Requirement for the addition of two matrices is, that they have the same number of rows and the same number of colums. So both matrices have to be an m-by-n matrix. The addition is made by adding each the components:<br/><br/>

Revision as of 14:14, 16 May 2014

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Requirement for the addition of two matrices is, that they have the same number of rows and the same number of colums. So both matrices have to be an m-by-n matrix. The addition is made by adding each the components:


\mathbf{A}+\mathbf{B}=
  \left[\begin{array}{cccc}
    a_{11} & a_{12} & \dots &a_{1n} \\
    a_{21} &\ddots & &\vdots\\
    \vdots & & & \\
    a_{m1} & \dots & & a_{mn}
  \end{array}\right]+
  \left[\begin{array}{cccc}
    b_{11} & b_{12} & \dots &b_{1n} \\
    b_{21} &\ddots & &\vdots\\
    \vdots & & & \\
    b_{m1} & \dots & &b_{mn}
  \end{array}\right]=
  \left[\begin{array}{cccc}
    a_{11}+b_{11} & a_{12}+b_{12} & \dots &a_{1n}+b_{1n} \\
    a_{21}+b_{21} &\ddots & &\vdots\\
    \vdots & & & \\
    a_{m1}+b_{m1} & \dots & &a_{mn}+b_{mn}
  \end{array}\right]

Example: Addition of two 3-by-3 matrices



\mathbf{A}_e+\mathbf{B}_e=
  \left[\begin{array}{ccc}
    1 & 3 & -2\\
    0 & -1 & 3\\
    2 & 4 & 2
  \end{array}\right]+
  \left[\begin{array}{ccc}
    -3 & 2 & -1\\
    2 & 4 & -3\\
    0 & -2 & 1
  \end{array}\right]=
  \left[\begin{array}{ccc}
    1-3 & 3+2 & -2-1\\
    0+2 & -1+4 & 3-3\\
    2+0 & 4-2 & 2-1
  \end{array}\right]=
  \left[\begin{array}{ccc}
    -2 & 5 & -3\\
    2 & 3 & 0\\
    2 & 2 & 1
  \end{array}\right]