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jverzani
2025-07-29 17:11:34 -04:00
parent 50cb645452
commit 8398f21b87
6 changed files with 9 additions and 9 deletions

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@@ -88,7 +88,7 @@ Vectors and matrices have properties that are generalizations of the real number
* Viewing a vector as a matrix is possible. The association chosen here is common and is through a *column* vector.
* The *transpose* of a matrix comes by permuting the rows and columns. The transpose of a column vector is a row vector, so $v\cdot w = v^T w$, where we use a superscript $T$ for the transpose. The transpose of a product, is the product of the transposes---reversed: $(AB)^T = B^T A^T$; the tranpose of a transpose is an identity operation: $(A^T)^T = A$; the inverse of a transpose is the tranpose of the inverse: $(A^{-1})^T = (A^T)^{-1}$.
* The *transpose* of a matrix comes by permuting the rows and columns. The transpose of a column vector is a row vector, so $v\cdot w = v^T w$, where we use a superscript $T$ for the transpose. The transpose of a product, is the product of the transposes---reversed: $(AB)^T = B^T A^T$; the transpose of a transpose is an identity operation: $(A^T)^T = A$; the inverse of a transpose is the transpose of the inverse: $(A^{-1})^T = (A^T)^{-1}$.
* Matrices for which $A = A^T$ are called symmetric.
@@ -133,7 +133,7 @@ The referenced notes identify $f'(x) dx$ as $f'(x)[dx]$, the latter emphasizing
We take the view that a derivative is a linear operator where $df = f(x+dx) + f(x) = f'(x)[dx]$.
In writing $df = f(x + dx) - f(x) = f'(x)[dx]$ generically, some underlying facts are left implicit: $dx$ has the same shape as $x$ (so can be added) and there is an underlying concept of distance and size that allows the above to be made rigorous. This may be an abolute value or a norm.
In writing $df = f(x + dx) - f(x) = f'(x)[dx]$ generically, some underlying facts are left implicit: $dx$ has the same shape as $x$ (so can be added) and there is an underlying concept of distance and size that allows the above to be made rigorous. This may be an absolute value or a norm.
##### Example: directional derivatives

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@@ -1790,7 +1790,7 @@ plotly()
nothing
```
Parallelogram formed by two vectors $\vec{v}$ and $\vec{w}$. What is desription of red diagonal?
Parallelogram formed by two vectors $\vec{v}$ and $\vec{w}$. What is a description of red diagonal?
:::
One diagonal is given by $\vec{v} + \vec{w}$. What is the other (as in the figure)?