146 Section 12: Calculating with Matrices

Using R0 and R1. To access a particular matrix element, store its row number in R0 and its column number in R1. These numbers won't change automatically (unless the calculator is in User mode).

To recall the element value (after storing the row and column numbers), press l followed by the letter key specifying the matrix.

To store a value in that element (after storing the row and column numbers), place the value in the X-register and press O followed by the letter key specifying the matrix.

Example: Store the value 9 as the element in row 2, column 3 of matrix A from the previous example.

Keystrokes

Display

 

2 O 0

2.0000

3 O 1

3.0000

9

9

 

O A

A

2,3

 

9.0000

Stores row number in R0. Stores column number in R1.

Keys the new element value into the X-register.

Row 2, column 3 of A. Value of a23.

Using the Stack. You can use the stack registers to specify a particular matrix element. This eliminates the need to change the numbers in R0 and R1.

To recall an element value, enter the row number and column number into the stack (in that order). Then press l followed by the letter key specifying the matrix. The element value is placed in the X-register. (The row and column numbers are lost from the stack.)

To store an element value, first enter the value into the stack followed by the row number and column number. Then press O followed by the letter key specifying the matrix. (The row and column numbers are lost from the stack; the element value is returned to the X-register.)

Note that these are the only operations in which the blue key precedes a gold letter key.

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HP 15c Scientific manual Keystrokes Display