The Quadf Menu - HP 49g+ User Manual

x A x
Finally,

The QUADF menu

The HP 49 G calculator provides the QUADF menu for operations related to
QUADratic Forms. The QUADF menu is accessed through „Ø.
This menu includes functions AXQ, CHOLESKY, GAUSS, QXA, and
SYLVESTER.
Function AXQ
In RPN mode, function AXQ produces the quadratic form corresponding to a
matrix A in stack level 2 using the n variables in a vector placed in stack
×
n n
level 1. Function returns the quadratic form in stack level 1 and the vector of
variables in stack level 1. For example,
[[2,1,-1],[5,4,2],[3,5,-1]] `
returns
2: '2*X^2+(6*Y+2*Z)*X+4*Y^2+7*Z*y-Z^2'
1: ['X' 'Y' 'Z']
2
T
X Y Z 5
3
2 X
X Y Z 5 X 4
3 X 5
x⋅A⋅x T 2 2 2
= 2X +4Y -Z +6XY+2XZ+7ZY
['X','Y','Z'] ` AXQ
1 1 X
4 2 Y
5 1 Z
Y Z
Y 2 Z
Y Z
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