deletions | additions       diff --git a/section_User_psychology_Programming_languages__.tex b/section_User_psychology_Programming_languages__.tex  index b83ec96..514162c 100644  --- a/section_User_psychology_Programming_languages__.tex  +++ b/section_User_psychology_Programming_languages__.tex 
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(symmetric) inner product to the (antisymmetric) outer product of Grassmann, - does it mean that he used the term also?  \paragraph{Gibbs (1884)}  Invents the terms ``dyad'' and ``dyadic''.  Recognizes the significance of the general product structure of the Ausdehnungslehre II and calls it the ``indeterminate product''.  \paragraph{Weierstrass (1884)~\cite{Weierstrass1884}}  Publishes the notion of defining formal linear algebra through its structure constants. (He does not give the numbers a name.) 
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Extends Weierstrass to give the restriction on the structure constants so that the resulting algebra is associative. (He does not give the numbers a name either.)  \paragraph{Heaviside (1885)}  States the scalar product as  \[  A B = A_1 B_1 + A_2 B_2 + A_3 B_3  \]  ``Its magnitude is A $\times$ that of B $\times$ the cosine of the angle between them''.  A statement familiar to all who have seen the scalar product! (Heaviside denotes the cross product, which he calls the vector product a la Hamilton, as $VAB$.)  Phil. Mag. S. 5. Vol. 19. No. 121. June 1885.   \url{http://www.tandfonline.com/doi/abs/10.1080/14786448508627695} 
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Starts with the abstract axioms of linear algebra and shows that the algebra may be represented by naturally by matrices and matrix multiplication. Also defines array as an ordered set with a known number of elements.  \paragraph{Wedderburn (1934) - Lectures on Matrices}  Starts with vectors as ordered sets of numbers as matrices as collections of coefficients in systems of linear equations.  Bilinear form $A(x, y) = \sum^n_{i,j=1} a_{ij} \xi_i \eta_j $ (\S 1.07, p. 9).  The scalar product is a particular bilinear form, $S x y$ (\S 1.07, p. 9), ``where $A = \Vert \delta_{ij} \Vert = 1$''. He also extends the scalar product to matrices (\S 5.02, p. 62), i.e. what we call today the Hadamard product, and also to tensors (\S 5.16, p. 81).  Using the $S$-prefix notation for scalar product he also writes the bilinear form as $A(x, y) = SxAy$.  He calls the outer product a ``tensor product'' (\S 5.09, pp. 72-73).  \url{http://www.maths.ed.ac.uk/~aar/papers/matrices.pdf}  Follows \cite{Scheffers1889}.  \paragraph{Ritt (1950)}