'returns a random integer less than A and greater than or equal to 0
DEF FNRN(A)=INT(RND(1)*A)

'rolls a die (singular of dice)
DEF FNDI=FNRN(6)+1

'returns true at the specified probability, otherwise false
'FNPR(.7) is true 70% of the time
DEF FNPR(P)=P>RND(1)

'flips a coin
DEF FNFC=FNPR(.5)

'Like mod but works correctly for negative values of A
'Useful for Pac-Man-style screen wrapping and many other things
DEF FNWR(A,B)=A-INT(A/B)*B

'hypotenuse
DEF FNHY(A,B)=SQR(A*A+B*B)

'distance between 2 points in 2 dimensions
DEF FND2(X1,Y1,X2,Y2)=SQR((X1-X2)^2+(Y1-Y2)^2)

'distance between 2 points in 3 dimensions
DEF FND3(X1,Y1,Z1,X2,Y2,Z2)=SQR((X1-X2)^2+(Y1-Y2)^2+(Z1-Z2)^2)

'volume of a sphere
DEF FNSV(R)=4.1888*R^3

'surface area of a sphere
DEF FNSA(R)=12.5664*R^2

Some handy GW-BASIC or QBASIC functions

Other