A fourth-order tensor relates two second-order tensors. Matrix notation of such relations is only possible, when the 9 components of the second-order tensor are . space equipped with coefficients taken from some good operator algebra. In this paper we introduce, using only the non-matricial language, both the classical (Grothendieck) projective tensor product of normed spaces. then the quotient vector space S/J may be endowed with a matricial ordering through .. By linear algebra, the restriction of σ to the algebraic tensor product is a.

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Not all math textbooks and papers are consistent in this respect throughout.

## Matrix calculus

In cases involving matrices where it makes sense, we give numerator-layout and mixed-layout results. The results of operations will be transposed when switching between numerator-layout and denominator-layout notation. Note that exact equivalents of the scalar product rule and chain rule do not exist when applied to matrix-valued functions of matrices.

For each of the various combinations, we give numerator-layout and denominator-layout results, except in the cases above where denominator layout rarely occurs. The tensor index notation with its Einstein summation convention is very similar to the matrix calculus, except one writes only a single component at a time.

As a first example, consider the gradient from vector calculus. Glossary of calculus Glossary of calculus. Accuracy disputes from July All accuracy disputes All articles with unsourced statements Articles with unsourced statements from July It is the gradient matrix, in particular, that finds many uses in minimization problems in estimation theoryparticularly in the derivation of the Kalman filter algorithm, which is of great importance in the field.

Each different situation will lead to a different set of rules, or a separate calculususing the broader sense of the term. This includes the derivation of:.

In these rules, “a” is a scalar. Not to be confused with geometric calculus or vector calculus. Similarly we will find that the derivatives involving matrices will reduce to derivatives involving vectors in a corresponding way.

The section on layout conventions discusses this issue in greater detail. In mathematicsmatrix calculus is a specialized notation for doing multivariable calculusespecially over spaces of matrices.

Also in analog with vector calculusthe directional derivative of a scalar f X of a matrix X in algbera direction of matrix Y is given by.

### [math/] Tensor Products in Quantum Functional Analysis: the Non-Matricial Approach

The vector and matrix derivatives presented in the sections to follow take full advantage of matrix notationusing a single variable to represent a large number of variables. July Learn how and when to remove this template message. Authors of both groups algebda write as though their specific convention were standard.

These can be useful in minimization problems found in many areas of applied mathematics and have adopted the names tangent matrix and gradient matrix respectively after their analogs for vectors. However, the product rule of this sort does apply to the differential form see belowand this is the way to derive many of the identities below involving the trace function, combined with the fact that the trace function allows transposing and cyclic permutation, i. Using numerator-layout notation, we have: An element of M 1,1 is a scalar, denoted with lowercase italic typeface: Matrix theory Linear algebra Multivariable calculus.

The two groups can be distinguished by whether they write the derivative of a scalar with respect to a vector as a column vector or a row vector. Here, we have used the term “matrix” in its most general sense, recognizing that vectors and scalars are simply matrices with one column and then one row respectively. Both of these conventions are possible even when the common assumption is made that vectors should be treated as column vectors when combined with matrices rather than row vectors.

However, many problems in estimation theory and other areas of applied mathematics would result in too many indices to properly keep track of, pointing in favor of matrix calculus in those areas.

In general, the independent variable can be a scalar, a vector, or a matrix while the dependent variable can be any of these as well. In the latter case, the product rule can’t quite be applied directly, either, but the equivalent can be done with a bit more work using the differential identities.

### Matrix calculus – Wikipedia

In physics, the electric field is the negative vector gradient of the electric potential. Note that a matrix can be considered a tensor of rank two.

These are the derivative of a matrix by a scalar and the derivative of a scalar by a matrix. The six kinds of derivatives that can be most neatly organized in matrix form are collected in the following table. Using denominator-layout notation, we have: However, even within a,gebra given field different authors can be found using competing conventions.

To convert to normal derivative form, first convert it to one of the following canonical forms, and then use these identities:. This only works well using the numerator layout. As another example, if we have tensoriak n -vector of dependent variables, or functions, of m independent variables we might consider the derivative of the dependent vector with respect to the independent vector. See the layout conventions section for a more detailed table. Differentiation notation Second derivative Third derivative Change of variables Implicit differentiation Related rates Taylor’s theorem.