1  REM  ****  HP BASIC PROGRAM LIBRARY  *******************************
2  REM
3  REM        INTEGR:   COMPUTER-AUGMENTED CALCULUS TOPICS
4  REM
5  REM        36667 REV  A   10/73
6  REM
7  REM  ****  CONTRIBUTED PROGRAM  ************************************
100  PRINT "THIS PROGRAM COMPUTES APPROXIMATIONS TO THE"
110  PRINT "DEFINITE INTEGRAL OF THE FUNCTION WHICH YOU"
120  PRINT "SUPPLIED ON LINE 250, OVER AN INTERVAL (A,B)."
130  PRINT 
140  PRINT "NOW TYPE A VALUE FOR A";
150  INPUT A
160  PRINT "TYPE A VALUE OF B";
170  INPUT B
180  IF A >= B THEN 460
190  PRINT "HOW MANY SUBINTERVALS DO YOU WANT [A,B] DIVIDED INTO";
200  INPUT N
210  LET N=INT(ABS(N))
220  LET S=0
230  LET W=(B-A)/N
240  FOR X=A TO B STEP W
250  LET Y=X^2-2*X
260  IF X=B THEN 300
270  IF X=A THEN 300
280  LET S=S+2*Y
290  GOTO 310
300  LET S=S+Y
310  NEXT X
320  LET T=((B-A)/(2*N))*S
330  PRINT 
340  PRINT 
350  PRINT "THE INTERVAL IS [";A;",";B;"]."
360  PRINT "THE NUMBER OF APPROXIMATING TRAPEZOIDS IS ";N
370  PRINT 
380  PRINT "THE APPROXIMATION IS ******";T;"******"
390  PRINT 
400  PRINT "TYPE THE CHANGE CODE";
410  INPUT C
420  IF C=2 THEN 140
430  IF C=1 THEN 190
440  IF C=3 THEN 500
450  GOTO 480
460  PRINT "A MUST BE LESS THAN B. TRY AGAIN."
470  GOTO 140
480  PRINT "THE CHANGE CODE MUST BE 1, 2, OR 3."
490  GOTO 400
500  END 
