(maxima.info)Functions and Variables for opsubst

---

Prev: opsubst-pkg Up: opsubst-pkg

---

Enter node , (file) or (file)node

76.1 Functions and Variables for opsubst
========================================

 -- Function: opsubst
          opsubst (<f>,<g>,<e>)
          opsubst (<g>=<f>,<e>)
          opsubst ([<g1>=<f1>,<g2>=<f2>,..., <gn>=<fn>],<e>)
     The function 'opsubst' is similar to the function 'subst', except
     that 'opsubst' only makes substitutions for the operators in an
     expression.  In general, When <f> is an operator in the expression
     <e>, substitute <g> for <f> in the expression <e>.

     To determine the operator, 'opsubst' sets 'inflag' to true.  This
     means 'opsubst' substitutes for the internal, not the displayed,
     operator in the expression.

     Examples:
          (%i1) load ("opsubst")$

          (%i2) opsubst(f,g,g(g(x)));
          (%o2)                     f(f(x))
          (%i3) opsubst(f,g,g(g));
          (%o3)                       f(g)
          (%i4) opsubst(f,g[x],g[x](z));
          (%o4)                       f(z)
          (%i5) opsubst(g[x],f, f(z));
          (%o5)                      g (z)
                                      x
          (%i6) opsubst(tan, sin, sin(sin));
          (%o6)                     tan(sin)
          (%i7) opsubst([f=g,g=h],f(x));
          (%o7)                       h(x)

     Internally, Maxima does not use the unary negation, division, or
     the subtraction operators; thus:
          (%i8) opsubst("+","-",a-b);
          (%o8)                     a - b
          (%i9) opsubst("f","-",-a);
          (%o9)                      - a
          (%i10) opsubst("^^","/",a/b);
                                       a
          (%o10)                       -
                                       b

     The internal representation of -a*b is *(-1,a,b); thus
          (%i11) opsubst("[","*", -a*b);
          (%o11)                  [- 1, a, b]

     When either operator isn't a Maxima symbol, generally some other
     function will signal an error:
          (%i12) opsubst(a+b,f, f(x));

          Improper name or value in functional position:
          b + a
           -- an error.  Quitting.  To debug this try debugmode(true);

     However, subscripted operators are allowed:
          (%i13) opsubst(g[5],f, f(x));
          (%o13)                     g (x)
                                      5

     To use this function write first 'load("opsubst")'.