怎样方便的得到这样的一个矩阵

derwille

知道矩阵
a= {{a1, a2, a3}, {b1, b2, b3}, {c1, c2, c3}};
b = {{aa1, aa2, aa3}, {bb1, bb2, bb3}, {cc1, cc2, cc3}};
要求一个9*9的矩阵c，就是a中的每一个元素都乘以b就得到这样一个9*9的矩阵c；
有没有方便的形式求？

eigen

用张量积中的

1. KroneckerProduct[a, b]

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结果是：

1. {{a1 aa1, a1 aa2, a1 aa3, a2 aa1, a2 aa2, a2 aa3, a3 aa1, a3 aa2, a3 aa3},
   
2. {a1 bb1, a1 bb2, a1 bb3, a2 bb1, a2 bb2, a2 bb3, a3 bb1, a3 bb2, a3 bb3},
   
3.   {a1 cc1, a1 cc2, a1 cc3, a2 cc1, a2 cc2, a2 cc3, a3 cc1, a3 cc2, a3 cc3},
   
4. {aa1 b1, aa2 b1, aa3 b1, aa1 b2, aa2 b2,  aa3 b2, aa1 b3, aa2 b3, aa3 b3},
   
5. {b1 bb1, b1 bb2, b1 bb3, b2 bb1, b2 bb2, b2 bb3, b3 bb1, b3 bb2, b3 bb3},
   
6. {b1 cc1, b1 cc2, b1 cc3, b2 cc1, b2 cc2,  b2 cc3, b3 cc1, b3 cc2, b3 cc3},
   
7.   {aa1 c1, aa2 c1, aa3 c1, aa1 c2, aa2 c2, aa3 c2, aa1 c3, aa2 c3, aa3 c3},
   
8. {bb1 c1, bb2 c1, bb3 c1, bb1 c2, bb2 c2,  bb3 c2, bb1 c3, bb2 c3, bb3 c3},
   
9. {c1 cc1, c1 cc2, c1 cc3, c2 cc1, c2 cc2, c2 cc3, c3 cc1, c3 cc2, c3 cc3}}

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eigen

或者用广义外积

1. ArrayFlatten[Outer[Times, a, b]]

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