Re: Re: simple iteration question

*To*: mathgroup at smc.vnet.net*Subject*: [mg89961] Re: [mg89928] Re: simple iteration question*From*: DrMajorBob <drmajorbob at att.net>*Date*: Wed, 25 Jun 2008 06:27:33 -0400 (EDT)*References*: <g3g017$l06$1@smc.vnet.net>*Reply-to*: drmajorbob at longhorns.com

I wonder if this is closer to the OP's intent: mat = {{3, 2, 1}, {5, 6, 1}, {10, 5, 1}}; vec = {1, 2, 3}; Catch[Fold[If[#1.#2 > 50, Throw[#1], #1 + #2] &, 0 vec, Prepend[mat, vec]]] {9, 10, 5} FoldList[(Print[{#1, #2, #1.#2, #1 + #2}]; #1 + #2) &, 0 vec, Prepend[mat, vec]] {{0,0,0},{1,2,3},0,{1,2,3}} {{1,2,3},{3,2,1},10,{4,4,4}} {{4,4,4},{5,6,1},48,{9,10,5}} {{9,10,5},{10,5,1},145,{19,15,6}} {{0, 0, 0}, {1, 2, 3}, {4, 4, 4}, {9, 10, 5}, {19, 15, 6}} Bobby On Tue, 24 Jun 2008 05:17:15 -0500, sashap <pavlyk at gmail.com> wrote: > On Jun 20, 5:16 am, Francisco Gutierrez <fgutiers2... at yahoo.com> > wrote: >> Dear Friends: >> I have a list of the form list={{3,2,1},{5,6,1},{10,5,1}}, of any lengt= > h >> I have a vector, say vector={1,2,3} >> I want to make the following iteration. Take the first component of th= > e = >> list, make the dot product of it and the vector, and substract a number >> (= > sa= >> y 50). If the result is bigger or equal than zero, stop and return the >> ve= > ct= >> or. If it is less than zero, then change the vector in the followig >> way: = > ve= >> ctor+list[[2]], and repeat the test. >> Iterate until the result is equal or bigger than zero, or until the >> list = > en= >> ds. >> I haven't found a neat way of doing this. Any help is welcome >> Francisco >> > > Hey Francisco, > > here is a short way of doing it: > > In[59]:= mat = {{3, 2, 1}, {5, 6, 1}, {10, 5, 1}}; > vec = {1, 2, 3}; > > In[61]:= Catch[ > Fold[If[#1.#2 > 50, Throw[#1], #1 + mat[[2]]] &, vec, mat]] > > Out[61]= {6, 8, 4} > > Oleksandr Pavlyk > > -- DrMajorBob at longhorns.com