# HP 50g User Manual Page 625

Graphing calculator.

With the calculator, in RPN mode, you can proceed as follows:
First, within your HOME directory, create a sub-directory to be called MPFIT
(Multiple linear and Polynomial data FITting) , and enter the MPFIT sub-
directory. Within the sub-directory, type this program:
«
and store it in a variable called MTREG (MulTiple REGression).
Next, enter the matrices X and b into the stack:
[[1,1.2,3.1,2][1,2.5,3.1,2.5 ][1,3.5,4.5,2.5][1,4,4.5,3][1,6,5,3.5]]
Press J@MTREG. The result is: [-2.1649...,–0.7144...,-1.7850...,7.0941...],
i.e.,
y = -2.1649–0.7144 x
You should have in your calculator's stack the value of the matrix X and the
vector b, the fitted values of y are obtained from y = X b, thus, just press *
to obtain: [5.63.., 8.25.., 5.03.., 8.22.., 9.45..].
x
1
1.20
3.10
2.50
3.10
3.50
4.50
4.00
4.50
6.00
5.00
X y « X TRAN X * INV X TRAN * y * " "
`` (keep an extra copy)
[5.7,8.2,5.0,8.2,9.5] `
x
x
2
3
2.00
2.50
2.50
3.00
3.50
-2
-1.7850 10
1
y
5.70
8.20
5.00
8.20
9.50
x
+ 7.0941 x
2
3
.
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