Exponentiation operator: Difference between revisions

An alternative to ipow that is about 30% faster (for 5**70) would be

<lang rexx>pp: Procedure

Parse Arg x,y

If x=0 & y<0 Then call errMsg x"**" y "is invalid"

yp=abs(y)

p.1=x

x.1=1

i=1

Do k=2 By 1 While i<=yp%2

i=2*i

kk=k-1

p.k=p.kk*p.kk

x.k=i

/* Say k i x.k p.k */

End

pp=1

Do i=k-1 To 1 By -1

If x.i<=yp Then Do

pp=pp*p.i

yp=yp-x.i

End

End

If y<0 Then

pp=1/pp

Return pp

</lang>