Re: Non-calculus vector math
- To: mathgroup at smc.vnet.net
- Subject: [mg75779] Re: Non-calculus vector math
- From: "David Rees" <w3bdevilREMOVE at THISw3bdevil.com>
- Date: Thu, 10 May 2007 05:18:17 -0400 (EDT)
- References: <200705080952.FAA18614@smc.vnet.net> <f1s17f$f7r$1@smc.vnet.net>
Lovely, thanks all :) "Murray Eisenberg" <murray at math.umass.edu> wrote in message news:f1s17f$f7r$1 at smc.vnet.net... > Since a vector in Mathematica may be represented by a list, such vector > algebra is just adding lists and multiplying lists by numbers. So you > can work your problem essentially the same way you would with paper and > pencil (except that you use braces to enclose a list instead of > > Easy: > > x0 = {3,6,-1}; v = 1000{1,-4,5}; > x0 + 35 v > {35003,-139994,174999} > > Or, if you'd like to use units: > > <<Units` (* load package *) > x0 = {3, 6, -1}; v = {1, -4, 5}/SI[Milli Second]; > x0 + 35 Second v > {35003,-139994,174999} > > In both cases, there was no actual need to give names to the initial > position position or velocity; I used names only in order to clarify > what was being done. (You might also introduce a name for the time, say > t1.) > > Notice that the above did not use the x i + y j + z k format. If you > want that, you can do it. Start with > > {i,j,k}={{1,0,0},{0,1,0},{0,0,1}}; > > or, in Mathematica 6.0: > > {i, j, k} = UnitVector[3, #] & /@ {1, 2, 3}; > > (Probably you would not want to usurp the letters i,j,k for this, since > they are so useful as counters, so it would be a better idea to use, > say, DoubleStruckI, DoubleStruckJ, DoubleStruckK. I cannot display > those in this plain-text message without going to Unicode, so I'm not > using them.) > > Then instead of the above you could calculate: > > x0=3i+6j-k; v=1000(i-4j+5k); > x0+35v > > (or you could again do it with units). With a bit more work, you could > display the result in the x i + y j + z k form. > > David Rees wrote: >> Ahoy, >> >> How can I perform elementary vector math in Mathematica? From what I've >> found, it's all Vector Calculus, but what about trivial/elementary vector >> math? >> >> Things like: "Particle A with position unit-vector of (3i+6j-1k) and >> velocity vector (1i-4j+5k)ms^-1 collides with Particle B 35 seconds after >> moving off from its initial position, where did it collide?" >> >> Thanks >> >> >> > > -- > Murray Eisenberg murray at math.umass.edu > Mathematics & Statistics Dept. > Lederle Graduate Research Tower phone 413 549-1020 (H) > University of Massachusetts 413 545-2859 (W) > 710 North Pleasant Street fax 413 545-1801 > Amherst, MA 01003-9305 >
- References:
- Non-calculus vector math
- From: "David Rees" <w3bdevilREMOVE@THISw3bdevil.com>
- Non-calculus vector math