Linear algebra introduction tensors and arrays

vec = {1, 2, 3}

{1, 2, 3}

Dimensions[vec]

{3}

tensor = { {{1, 2, 3, 4}, {4, 5, 6, 7}, {4, 5, 6, 7}}, {{1, 2, 3, 9}, {1, 2, 6, 5}, {1, 2, 6, 5}}}

{{{1, 2, 3, 4}, {4, 5, 6, 7}, {4, 5, 6, 7}}, {{1, 2, 3, 9}, {1, 2, 6, 5}, {1, 2, 6, 5}}}

Dimensions[tensor]

{2, 3, 4}