- #1
rocomath
- 1,755
- 1
Suppose
[tex]A\overrightarrow{x}=\lambda_1\overrightarrow{x}[/tex]
[tex]A\overrightarrow{y}=\lambda_2\overrightarrow{y}[/tex]
[tex]A=A^T[/tex]
Take dot products of the first equation with [tex]\overrightarrow{y}[/tex] and second with [tex]\overrightarrow{x}[/tex]
ME 1) [tex](A\overrightarrow{x})\cdot \overrightarrow{y}=(\lambda_1\overrightarrow{x})\cdot\overrightarrow{y}[/tex]
BOOK ... skipped steps but only shows this 1) [tex](\lambda_1\overrightarrow{x})^T\overrightarrow{y}=(A\overrightarrow{x})^T\overrightarrow{y}=\overrightarrow{x}^TA^T\overrightarrow{y}=\overrightarrow{x}^TA\overrightarrow{y}=\overrightarrow{x}^T\lambda_2\overrightarrow{y}[/tex]
Now it looks like I have to transpose my first step, but if I do so, do I assume that [tex]y=y^T[/tex]?
[tex]A\overrightarrow{x}=\lambda_1\overrightarrow{x}[/tex]
[tex]A\overrightarrow{y}=\lambda_2\overrightarrow{y}[/tex]
[tex]A=A^T[/tex]
Take dot products of the first equation with [tex]\overrightarrow{y}[/tex] and second with [tex]\overrightarrow{x}[/tex]
ME 1) [tex](A\overrightarrow{x})\cdot \overrightarrow{y}=(\lambda_1\overrightarrow{x})\cdot\overrightarrow{y}[/tex]
BOOK ... skipped steps but only shows this 1) [tex](\lambda_1\overrightarrow{x})^T\overrightarrow{y}=(A\overrightarrow{x})^T\overrightarrow{y}=\overrightarrow{x}^TA^T\overrightarrow{y}=\overrightarrow{x}^TA\overrightarrow{y}=\overrightarrow{x}^T\lambda_2\overrightarrow{y}[/tex]
Now it looks like I have to transpose my first step, but if I do so, do I assume that [tex]y=y^T[/tex]?
Last edited: