JS implements simple two-dimensional matrix product operation

JS implements simple two-dimensional matrix product operation_javascript skills

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Release： 2016-05-16 15:17:59

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The example in this article describes how to implement a simple two-dimensional matrix product operation using JS. Share it with everyone for your reference, the details are as follows:

The screenshot of the Console console is as follows:

(The above picture shows the output result directly put into the code (the premise that matrix A can be multiplied by matrix B is that the number of columns of matrix A is equal to the number of rows of matrix B)

<!DOCTYPE html>
<html>
  <head>
    <title>demo</title>
  </head>
  <body>
  </body>
  <script type="text/javascript">
    function log(msg) {
      console.log(msg);
    }
    /**
    * 可视化的打印出矩阵的数据
    */
    function printMatrixData(data) {
      console.log(data);
      if(!data) {
        return;
      }
      var numberSize = 5;
      for(var i=0, len=data.length; i<len; i++) {
        var row = data[i];
        var rowLog = "(";
        for(var j=0, jLen=row.length; j<jLen; j++) {
          rowLog += row[j];
          // 补齐空格
          rowLog += indent(numberSize - (row[j]+"").length);
        }
        rowLog+=")";
        console.log(rowLog);
      }
    }
    /**
    * 拼接指定长度的空格
    */
    function indent(length) {
      var empty = "";
      for(var i=0; i<length; i++) {
        empty += " ";
      }
      return empty;
    }
    /**
    * 矩阵原型
    */
    function Matrix(data) {
      // 这里必须传一个二维数组，最好严格检验一下
      if(typeof data !== "object" || typeof data.length === "undefined" || !data) {
        throw new Error("data's type is error");
      }
      this.data = data;
      this.cols = data.length;
    }
    var M = {
      findByLocation: function(data, xIndex, yIndex) {
        if(data && data[xIndex]) {
          return data[xIndex][yIndex];
        }
      },
      // 矩阵乘积
      multiply: function(m, n) {
        if(!m instanceof Matrix && !n instanceof Matrix) {
          throw new Error("data's type is error");
        }
        var mData = m.data;
        var nData = n.data;
        if(mData.length == 0 || nData.length == 0) {
          return 0;
        }
        if(mData[0].length != nData.length) {
          throw new Error("the two martrix data is not allowed to dot");
        }
        var result = [];
        for(var i=0, len=mData.length; i<len; i++) {
          var mRow = mData[i];
          result[i] = [];
          for(var j=0, jLen=mRow.length; j<jLen; j++) {
            var resultRowCol = 0;
            // 如果n矩阵没有足够的列数相乘，转入m矩阵下一行
            if(typeof this.findByLocation(nData, 0, j) === "undefined") {
              break;
            }
            for(var k=0, kLen=jLen; k<kLen; k++) {
              resultRowCol += mRow[k]*this.findByLocation(nData, k, j);
            }
            result[i][j] = resultRowCol;
          }
        }
        return result;
      }
    };
    var m = new Matrix([[2, -1], [-2, 1], [-1, 2]]);
    var n = new Matrix([[4, -3], [3, 5]]);
    var result = M.multiply(m, n);
    printMatrixData(result);
    var m2 = new Matrix([[2, 3, 1], [5, 2, 4], [-3, 2, 0]]);
    var n2 = new Matrix([[11], [5], [8]]);
    var result2 = M.multiply(m2, n2);
    printMatrixData(result2);
  </script>
</html>

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