Description of fast matrix multiplication algorithm: ⟨2×4×9:58⟩

Algorithm type

8⁢X2⁢Y4⁢Z2+6⁢X2⁢Y2⁢Z2+8⁢X⁢Y4⁢Z+2⁢X⁢Y3⁢Z+8⁢X⁢Y2⁢Z+26⁢X⁢Y⁢Z8X2Y4Z26X2Y2Z28XY4Z2XY3Z8XY2Z26XYZ8*X^2*Y^4*Z^2+6*X^2*Y^2*Z^2+8*X*Y^4*Z+2*X*Y^3*Z+8*X*Y^2*Z+26*X*Y*Z

Algorithm definition

The algorithm ⟨2×4×9:58⟩ could be constructed using the following decomposition:

⟨2×4×9:58⟩ = ⟨2×4×4:26⟩ + ⟨2×4×5:32⟩.

This decomposition is defined by the following equality:

Trace⁡Mul⁡A_1_1A_1_2A_1_3A_1_4A_2_1A_2_2A_2_3A_2_4B_1_1B_1_2B_1_3B_1_4B_1_5B_1_6B_1_7B_1_8B_1_9B_2_1B_2_2B_2_3B_2_4B_2_5B_2_6B_2_7B_2_8B_2_9B_3_1B_3_2B_3_3B_3_4B_3_5B_3_6B_3_7B_3_8B_3_9B_4_1B_4_2B_4_3B_4_4B_4_5B_4_6B_4_7B_4_8B_4_9C_1_1C_1_2C_2_1C_2_2C_3_1C_3_2C_4_1C_4_2C_5_1C_5_2C_6_1C_6_2C_7_1C_7_2C_8_1C_8_2C_9_1C_9_2=Trace⁡Mul⁡A_1_1A_1_2A_1_3A_1_4A_2_1A_2_2A_2_3A_2_4B_1_1B_1_2B_1_3B_1_4B_2_1B_2_2B_2_3B_2_4B_3_1B_3_2B_3_3B_3_4B_4_1B_4_2B_4_3B_4_4C_1_1C_1_2C_2_1C_2_2C_3_1C_3_2C_4_1C_4_2+Trace⁡Mul⁡A_1_1A_1_2A_1_3A_1_4A_2_1A_2_2A_2_3A_2_4B_1_5B_1_6B_1_7B_1_8B_1_9B_2_5B_2_6B_2_7B_2_8B_2_9B_3_5B_3_6B_3_7B_3_8B_3_9B_4_5B_4_6B_4_7B_4_8B_4_9C_5_1C_5_2C_6_1C_6_2C_7_1C_7_2C_8_1C_8_2C_9_1C_9_2

N.B.: for any matrices A, B and C such that the expression Tr(Mul(A,B,C)) is defined, one can construct several trilinear homogeneous polynomials P(A,B,C) such that P(A,B,C)=Tr(Mul(A,B,C)) (P(A,B,C) variables are A,B and C's coefficients). Each trilinear P expression encodes a matrix multiplication algorithm: the coefficient in C_i_j of P(A,B,C) is the (i,j)-th entry of the matrix product Mul(A,B)=Transpose(C).

Algorithm description

These encodings are given in compressed text format using the maple computer algebra system. In each cases, the last line could be understood as a description of the encoding with respect to classical matrix multiplication algorithm. As these outputs are structured, one can construct easily a parser to its favorite format using the maple documentation without this software.

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