Fast Second-Order Orthogonal Tensor Subspace Analysis for Face Recognition

Table 1

Time complexity of TSA, DTSA, OTSA-N, ODTSA-N, OTSA-NL, and ODTSA-NL.

Method	Time complexity
TSA	2𝑙1+𝑙2𝐿1𝐿2+4𝑙1𝐿^22+4𝑙2𝐿^21𝑁+66𝐿^31+𝐿^32
DTSA	2𝑙1+𝑙2𝐿1𝐿2+2𝑙1𝐿^22+2𝑙2𝐿^21(𝑁+𝐶)+66𝐿^31+𝐿^32
OTSA-N	2𝑙1+𝑙2𝐿1𝐿2+4𝑙1𝐿^22+4𝑙2𝐿^21𝑁+9𝑇𝐿^31+𝐿^32
ODTSA-N	2𝑙1+𝑙2𝐿1𝐿2+2𝑙1𝐿^22+2𝑙2𝐿^21(𝑁+𝐶)+9𝑇𝐿^31+𝐿^32
OTSA-NL	2𝑙1+𝑙2𝐿1𝐿2+4𝑙1𝐿^22+4𝑙2𝐿^21𝑁+2𝑇𝑙1𝐿^21+𝑙2𝐿^22
ODTSA-NL	2𝑙1+𝑙2𝐿1𝐿2+2𝑙1𝐿^22+2𝑙2𝐿^21(𝑁+𝐶)+2𝑇𝑙1𝐿^21+𝑙2𝐿^22