Radio Shack TRS-80 Model 100 Basic Manual page 145

Experiment #6 Computing the Median
of the First N Values
The previous program will be changed so that only the first N values will be read in
from the RAM file, instead of all 30. The median of these N values will then be
computed and displayed.
You will be able to input the value for N when the program is executed. The main
purpose of this experiment is to generalize the median calculation, and show you how
to determine whether there are an even or an odd number of values.
Make the following changes to the program:
20 INPUT "NUMBER OF DAYS (2 - 30)"; N
30 FOR I = 1 TO N
550 N1=INT«N+1)/2) :
N2=INT~(N+2)/2)
560 MO = (S (N 1) + S (N2» / 2
570 PRINT "MEDIAN IS"; MO
List the program to verify that it is:
5 OPEN "RAM:SALEOA.OO" FOR INPUT AS 1
10 DIM S(30)
20 INPUT "NUMBER OF DAYS (2 - 30)"; N
30 FOR I = 1 TO 30
L10 INPUT
#
1
t
S(I)
50 NEXT I
500 FOR I = 1 TO N - 1
510 FOR J = 1 TO N - I
520 IF S(J)
<
S(J + 1) GOTO
5L10
530 S=S(J) : S(J)=S(J+l) : S(J+l)=S
5L10
NEXT J : NEXT I
550 N1=INT«N+1>/2) : N2=INT«N+2)/2)
560 MO = (S (N 1) + S (N2» / 2
570 PRINT "MEDIAN IS"; MO
Execute the program.
This time you will be prompted for the number of days of sales to be read. After you
enter a value, the program will read the first N values from the RAM file and display
the median.
Here is an example of the execution and output of the program:
NUMBER OF DAYS (2 - 30)? 20
MEDIAN IS 285
Thus the median of the first 20 sales is 285.
Execute the program several times. Try entering both even and odd values for N. You
will find that the program will correctly calculate the median in every case.
Line 20 An INPUT statement has been added which prompts you to enter the value
for N.
139