功能:求解Sylvester方程

格式:
[X, er] = SolveEquationBySylvester(A, B, C)

A : m * m 方阵矩阵变量
B : n * n 方阵矩阵变量
C : m * n 方阵矩阵变量

X : 求解得到的m * n矩阵变量
er: 求解结果的误差平方和

说明:
1、本函数主要求解如下线性方程组
$$
AX+XB=C
$$

例子:
a =
[ 2.44395618254503    0.67281273970045    0.98574446001357
  0.18181896404447    0.16796413071824    3.15660299880272
  2.61141725192378    2.37797570153045    3.60558274742476 ]
b =
[ 2.73102027211851    3.90412138863659    3.32402518918925
  0.54168868183237    5.50940119452281    1.45748385854880
  1.64493946807689    0.42245334033968    2.66299302254943 ]
c =
[ 6.43443203644568    6.50606063311271    5.88154190307555
  1.95053311155668    3.99319857544880    5.70002940562555
  1.63939497323679    6.06418669878700    0.69482288169433 ]
x = SolveEquationBySylvester(a,b,c)//回车得到如下结果, 可以通过命令验证结果是否为0: Mul(a,x) + Mul(x,b) - c 
x =
[ 1.04611614517795    0.23673683365599    0.35631621948211
  2.18489278331490   -1.65686386463159    0.03034941978997
 -1.18040162161074    1.52501563362494    0.22224528838057 ]
