How to assign values to variables

[Paul RIVIER , Mon, 05 Dec 2005 15:47:01 +0000]:
> I am looking for a way to assign Fm elements to U elements,
> element-per-elements.
> I mean that at the end of the process, typing U1y; should return cos(x)
> for exemple, or U2x; should return sin(x)^2.

Here is the simplest way I have come up with, but I am sure it should
be possible much simpler.  The problem is that ":" cannot be mapped,
in which case you would just write map(":", U, Fm).  Instead, the
following works:

  (%i12) U:MATRIX([U1x],[U1y],[U2x],[U2y]);
  
                                        [ U1x ]
                                        [     ]
                                        [ U1y ]
  (%o12)                                [     ]
                                        [ U2x ]
                                        [     ]
                                        [ U2y ]
  (%i13) Fm:MATRIX([SIN(x)],[COS(x)],[SIN(x)^2],[ATAN(x)]);
  
                                      [ SIN(x)  ]
                                      [         ]
                                      [ COS(x)  ]
  (%o13)                              [         ]
                                      [    2    ]
                                      [ SIN (x) ]
                                      [         ]
                                      [ ATAN(x) ]
  (%i15) map(lambda([l,v], buildq([l:inpart(l,1),v:inpart(v,1)],
                                  lambda([],l : v))()), 
             U, Fm);
  
                                                     2
  (%o15)                   MATRIX(SIN(x), COS(x), SIN (x), ATAN(x))
  (%i16) U2y;
  
  (%o16)                                    ATAN(x)
  (%i17) 
  (%i17) U2x;
  
                                               2
  (%o17)                                    SIN (x)
  
However, the buildq([...], lambda([]))() idiom for forcing evaluation
is not really pretty.

HTH,

Albert.