Re: Please answer to my questions,thank you.

*To*: mathgroup at smc.vnet.net*Subject*: [mg95133] Re: Please answer to my questions,thank you.*From*: David Bailey <dave at removedbailey.co.uk>*Date*: Wed, 7 Jan 2009 04:12:01 -0500 (EST)*References*: <gjsg8r$jvp$1@smc.vnet.net>

olfa mraihi wrote: > Hello Mathematica community, > First, wish you happy new year. > I want to know how to do these points with mathematica: > > 1-reduce: f(f(f(...(v) i times=f(f(f(...(w) j times. I've tried "nest" like this: > Nest[f,v,i]=C5 Nest[f,w,j] > , but I have this error: > Nest::intnm: Non-negative machine-size integer expected at position 3 in Nest[f,v,i] and > Nest::intnm: Non-negative machine-size integer expected at position 3 in Nest[f,w,j] > =C2 > 2-I want to use lists symbollically like this: m, mP,l,lP are lists, j,jP,i,iP are variables.By symbolically I mean without specifying the concrete > elements and the concrete length of these lists > i<=iP,j-Length[m]=C5 jP-Length[mP], > Join[l,m]=C5 Join[lP,mP], > Nest[Rest,m,i]=C5 Nest[Rest,mP,iP] > > 3-when I have j<N and i==j+1 I want mathematica to give me i==N as result. > > 4-solve this system of equations: xP = 1 + a/yP=C2 and |yP-xP| <= epsilon > > Thank you very much. > Yours faithfully, > Olfa MRAIHI > To take just one of your requests: The built-in lists in Mathematica are of fixed length, although the elements themselves can be variables: {a,b,c} However, you can write patterns that describe lists of unknown length: {a,b,c,___} More generally, I suggest you step back a bit, and describe the actual problem you are trying to solve. David Bailey http://www.dbaileyconsultancy.co.uk