功能:符号矩阵减法

格式:[c, k] = SymMatrixSub(a, b)

a :符号矩阵对象变量
b :和a同纬数的符号矩阵对象变量

c :返回的a-b符号矩阵对象变量
k :执行成功与否的标志,如果k为1表示执行成功,返回0表示a、b参数有误

例子:

a = SymMatrix([ 
"a00","a01","a02" 
"a10","a11","a12" ])

b = SymMatrix([
"b00","b01","b02" 
"b10","a11","b12" ])

c = SymMatrixSub(a, b)//回车得到如下结果
c = {
a00-b00 , a01-b01 , a02-b02
a10-b10 , 0       , a12-b12 }