I would like to model the kinematics of a collection of points in R^3 - which represent atoms  on a molecule - using Maple. I want to specify the fixed distances between the points.  I just saw a formula in a book I own for the number of degrees of freedom of such a system. I wil have plenty of degrees of freedom with which to work. So, I will begin - in the simplest case - by arbitrarily specifying as many of the coordinates for the points as possible.

Does anyone have an idea of how best to program such a model?

I tried something like

I just typed an expression, such as

expand((z-6+I)*((5-I)*z+9));

on a line. On the next line, I wish to evaluate this expression at at z = 4+I, say,

without having to retype the expression. How do I do this?

%

simply returns the previous line.

I am in a mode with a red arrow on the left.

How do I define f to be an algebraic function of x over C, the complex numbers, such as

f(x)=x+7+I

I want to be able to plug in complex numbers for x and have a complex number

returned, say

f(9-5*I)=16-4*I

Thank you everyone for all your help. However, what I am leading up to in my research requires that I overcome the following hurdle. Let p[m] represent an unspecified function of three variables, e1, e2, and e3. (In reality, the explicit formula for the function is known, but I will not use that formula.) m is an index. So, p[1], p[2], p[3] etc are different functions of e1, e2, e3. I need to program an operator, T, which acts on p[m] and returns - symbolically - T(p[m]) = 1*e1*diff(p[m],e1) + 2*e2*diff(p[m],e2) + 3*e3*diff(p[m],e3) In case anyone has guessed already, T has gone under such

Simplest example I can think of. I want to define f(x) to be the absolute value function (yes, of course, without using the built-in Maple absolute value function) f:=x->x; is great for defining a function. I've used that many times to define n-vector-valued functions of m variables. But how do I do f:=x->x if x>0 f:=x->-x if x