A Cloud-Computing-Based Data Placement Strategy in High-Speed Railway

Algorithm 1

Formal description.

Formal description of a semi-definite programming problem

Solution:

  min∑^𝑛_𝑖≠𝑗𝐶(𝑖,𝑗)⋅𝑙_𝑖⋅𝑙_𝑗

 Satisfying:

   𝑙_𝑖,𝑙_𝑗 are unit vectors; 𝑙_𝑖⋅𝑖=1

   𝑙_𝑖 and 𝑙_𝑗 form the matrix 𝐿=[𝑙_𝑖⋅𝑙_𝑗] and all its

  eigenvalues are greater than or equal to 0,

  that is, matrix 𝐿 is semi-definite.