2016-07-24 131 views
3

数学,我可以通过做张量积计算内置Dot[],例如,这里是一个张pts6是否有C库实现张量积?

SeedRandom[10]; 
pts = RandomReal[1, {7, 7, 7, 5, 6, 5}]; 

(*coeffs = {c1, c2, c3, c4}*) 
coeff = BernsteinBasis[#1, Range[0, #1], #2] & @@@ 
      [email protected]{(Dimensions[pts, 4] - 1), {0.1, 0.2, 0.3, 0.4}}; 
(* 
{{0.531441,0.354294,0.098415,0.01458,0.001215,0.000054,1.*10^-6}, 
{0.262144,0.393216,0.24576,0.08192,0.01536,0.001536,0.000064}, 
{0.117649,0.302526,0.324135,0.18522,0.059535,0.010206,0.000729}, 
{0.1296,0.3456,0.3456,0.1536,0.0256}} 
*) 

(*do tensor product calculation ---> c4.(c3.(c2.(c1.pts))) *) 
Fold[#2.#1 &, pts, coeff] 

enter image description here

enter image description here

我Google关键词tensor product in C,然后我发现大多数张量库都是用C++编写的,而不是ANSI C编写的。

,所以我想知道:

  • Ç库,实现了Dot[]操作?
+1

您可能必须使用带有C接口的BLAS矩阵产品例程(如[cblas_gemm()](https://software.intel.com/zh-cn/node/520775)来模拟张量积。它基本上是重做那些C++张量库所做的。 – kangshiyin

+0

@ kangshiyin感谢您的建议。事实上,我需要一个张量积的c库来通过* Mathematica LibraryLink * wrapper实现'b-spline函数'。请参阅[这里](http://mathematica.stackexchange.com/questions/120384/why-does-this-librarylink-function-crash) – xyz

+0

我相信它也可以通过矩阵产品来实现。 – kangshiyin

回答

3

您可能不得不使用BLAS矩阵产品例程,如带有C接口的​​来模拟张量积。它基本上是重做那些C++张量库所做的。

你的张量积

c1(1x7) * pts(7x7x7x5x6x5) 

可以被看作是一个矩阵乘积

c1(1x7) * mat_pts(7x(7*7*5*6*5*6)) 

pts其中是6-d张量,但mat_pts是2- d矩阵。

因此,您可以使用矩阵乘积来计算张量积。