Array Menu - HP -28S Quick Reference

General • Arrays (or fields) are either vectors or matrices.
• Arrays can be real or complex.
• If an array contains a single complex value the entire array is
automatically complex.
• Lengthy array operations can be interrupted by pressing ON
• Arrays are entered by using square brackets [ and ].
• Example 2x2 matrix: [[1 2] [3 4]]
+ − Add/substract vectors or matrices of matching dimensions.
This also works on mixed real/complex arguments but if a complex
argument is involved the result will always be complex.
* Multiplication. Either operand may be real or complex:
• Multiply vector by number or number by vector → vector
• Multiply matrix by number or number by matrix → matrix
• Multiply matrix by vector → vector
• Multiply matrix by matrix → matrix
÷ • Calculate matrix X so that M1*X=M2 where M1 and M2 are matrices in
stack level 1 and 2. Or: B A ÷ calculates X=B/A so that AX=B.
• Calculate vector X so that M1*X=V2 where M1 and V2 are the matrix
and vector in level 1 and 2. Or: V M ÷ calculates X=V/M so the M*X=V.
These operations produce more accurate results then using the INV
command on matrices. The matrices must be square. Can often be used
even if the matrix A or M is singular and thus solves systems where the
number of variables does not match the number of equations.
INV (1/x) Returns inverse of square matrix.
SQ (x²) Returns the square of a square matrix.
→ARRY Convert stack values into a matrix or vector:
• X1 X2 ... Xn n →ARRY results in vector [X1 X2 ... Xn]
• X11 X12 ... Xnm {n m} →ARRY results in matrix [[X11...X1m] ...
[Xn1...Xnm]]
• Note that combining a number of vectors into a matrix is not possible!
•
An error occurs if the stack doesn't hold enough values for the matrix or
if they are not of numerical type.
•
If any one value on the stack is complex the resulting array will be
complex.
The inverse operation of →ARRY. Vector and matrix dimensions are
ARRY→
returned as a number or length-2 list in stack level 1.
PUT Replace value of a matrix or vector:
• V {idx} X PUT puts the number X into vector V at position idx and
returns the modified vector in level 1.
• M {row col} X PUT puts the number X into matrix M at position
(row,col) and returns the modified matrix in level 1.
•
'Nam' {idx} X PUT puts the number X into vector named Nam at
position idx and returns nothing.
When P2 is invoked it calls P1 with the values in stack level 1 and 2
and adds the results that P1 produced (which is ln(x²)+1).

ARRAY Menu

HP-28S
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