IBM 5100 Apl Reference Manual

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Inner Product Operator (.I 0
The symbol for the inner product operator is • (period). The inner product opera-
tor is used to combine any two primitive scalar dyadic functions and cause them to
operate on an array. An example of its use would be in matrix algebra. in finding
the matrix product of two matrices. The form for inner product is: A <D.@ B,
where(Dand @are any primitive scalar dyadic fun,ctions. Function@is performed
first and
then(Dreduction is applied between the results of function®.
The result is an array; the shape of the array is all but the last coordinate of
argument A catenated to all but the first coordinate of argument B (-1 {- pA)'(1 {- pB).
If argument A and argument B are matrices, the elements in each row of argument A
are acted
on by the elements in each column of argument B:
A~-2
2p1
")
.:-
3
'+
B~-2
r) I::'
.:..P,J 6 '7 8
A
6
8 ~--------(1x5) + (2x7) = 19
ri::.2
A
+.
XB
1.J·3 ~50
The above example is t~e same as doing the following for each element in the result:
( 1.x5)+(2x'l)
19
(:l.x6)+(2x8)
22
4·3
(3x6)+(4·xS)
50
, 113

IBM 5100 Specifications

General

Brand	IBM
Model	5100
Category	Laptop
Language	English