Entrywise matrix multiplication (Hadamard or Schur multiplication)

denhelden · April 25, 2014, 06:10

Hi,

i have a really simple question, but i didn't find the answer in the forum search or the programmer manual. I'd like to multiply two volScalarFields entrywise. This is also called Hadamard or Schur product.

Example: A ○ B = C with c11 = a11 * b11 (similar to the matrix addition)

How is this done in OpenFoam?

Thanks in advance
Thilo

fumiya · April 26, 2014, 14:50

Hi,

You might want to try

volScalarField C = A * B; //C[celli]=A[celli]*B[celli] where A[celli]: value of A at celli-th cell center

Hope this helps,
Fumiya

denhelden · April 28, 2014, 05:16

Hi Fumiya,

thanks for your answer. I thought, * would be the Outer Product in OpenFoam when handeling tensors. So it is defined in another way with matrixVolFields? I have found over the weekend the function cmptMultiply. Is the result the same? Is there a recommendation for which function to use?

Greetings
Thilo

mrishi · July 18, 2019, 07:15

Hi,
Did you find the implementation of Hadamard product?

Regards,
mrishi

April 25, 2014, 06:10	Entrywise matrix multiplication (Hadamard or Schur multiplication)	#1
denhelden New Member Thilo Franke Join Date: Mar 2014 Location: Bunswick Posts: 4 Rep Power: 12	Hi, i have a really simple question, but i didn't find the answer in the forum search or the programmer manual. I'd like to multiply two volScalarFields entrywise. This is also called Hadamard or Schur product. Example: A ○ B = C with c11 = a11 * b11 (similar to the matrix addition) How is this done in OpenFoam? Thanks in advance Thilo

April 26, 2014, 14:50		#2
fumiya Senior Member Fumiya Nozaki Join Date: Jun 2010 Location: Yokohama, Japan Posts: 266 Blog Entries: 1 Rep Power: 18	Hi, You might want to try volScalarField C = A * B; //C[celli]=A[celli]*B[celli] where A[celli]: value of A at celli-th cell center Hope this helps, Fumiya __________________ [Personal] Blog: https://caefn.com/ Twitter: https://twitter.com/FumiyaNozaki SlideShare: http://www.slideshare.net/fumiyanozaki96

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April 28, 2014, 05:16		#3
denhelden New Member Thilo Franke Join Date: Mar 2014 Location: Bunswick Posts: 4 Rep Power: 12	Hi Fumiya, thanks for your answer. I thought, * would be the Outer Product in OpenFoam when handeling tensors. So it is defined in another way with matrixVolFields? I have found over the weekend the function cmptMultiply. Is the result the same? Is there a recommendation for which function to use? Greetings Thilo

July 18, 2019, 07:15		#4
mrishi Member Rishikesh Join Date: Apr 2016 Posts: 63 Rep Power: 9	Hi, Did you find the implementation of Hadamard product? Regards, mrishi