ruby:NoMethodError (private method `new' called for Matrix:Class)出现问题，怎么解决?

重复其他人ruby代码结果时一个地方出错:
require 'Matrix'
def readMatrix(file)
colHeader = getHeader(file)
colHeader.delete_at(0)

rowHeader = []
matrix = []

tabRead(file,header=true){|arr|
rowHeader << arr.delete_at(0)
matrix << arr

}

return Matrix.new(matrix,colHeader,rowHeader)
end
出错提示为
ruby:NoMethodError (private method `new' called for Matrix:Class)
什么是private method，怎么结局?

private method `new'
说明  Matrix:Class 这个类的构造函数不允许直接调用，你可以看下文档。