problem 64

[Volker Vanoni]

Again a problem from Project Euler.net
The loop in the main function does not work and I don not know why.
If you enter single values everything is ok.
#COMPILE EXE
#DIM ALL

FUNCTION PBMAIN () AS LONG
DIM str AS STRING
DIM j AS LONG,s AS LONG, s1 AS LONG
s = 0
FOR j = 2 TO 10000
str = sqrtcfrac(j)
s1 = add(str)
IF s1 MOD 2 > 0 THEN
s+=1
END IF
NEXT j
PRINT s


WAITKEY$

END FUNCTION
FUNCTION sqrtcfrac(n AS LONG) AS STRING
DIM a AS LONG, w AS LONG, w2 AS LONG, q AS LONG, q0 AS LONG, q1 AS LONG, m AS LONG, m1 AS LONG
DIM st AS STRING
st = ""
w = INT(SQR(n))
q = n - w*w
IF q = 0 THEN
sqrtcfrac = STR$(w)+st
END IF
w2 = 2*w
a = w
m = w
q0 = 1
st = STR$(a)+" " + st
WHILE NOT a = w2
a = (m+w) \ q
st = st + STR$(a)+","
m1 = a*q - m
q1 = q0 + a*(m - m1)
m = m1
q0 = q
q = q1
WEND
sqrtcfrac = st
END FUNCTION

FUNCTION add(st AS STRING) AS LONG
DIM i AS LONG, c AS LONG
c = 0
FOR i = 1 TO LEN(st)
IF MID$(st,i,1) = "," THEN
c+=1
END IF
NEXT i
add = c
END FUNCTION

regardxs
Volker

[Michael Mattias]

Please use code tags when posting code.

http://www.powerbasic.com/support/pbforums/misc.php?do=bbcode

[Paul Dixon]

Volker,
running your program as posted gives a "divide by zero" error because the value if q becomes zero inside the While/Wend loop so the line a = (m+w) \ q cannot be calculated.

Paul.

[Guy Dombrowski]

Volker,
Add #DEBUG DISPLAY ON before #COMPILE EXE and the compiler will tell you what kind of error you have

[Volker Vanoni]

re: Problem 64

Paul,
thank you for your hint. At first I did not believe it, because I have a clause to handle y = 0. But that is not enough in Powerbasic. Before "end if" you have to insert "exit function". Now everything works well
Volker