maxima-online.org

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

Q

R

S

T

U

V

W

X

Y

Z

Subst

Function: subst (<a>, <b>, <c>) Substitutes <a> for <b> in <c>. <b> must be an atom or a complete subexpression of <c>. For example, x+y+z is a complete subexpression of 2*(x+y+z)/w while x+y is not. When <b> does not have these characteristics, one may sometimes use substpart or ratsubst (see below). Alternatively, if <b> is of the form e/f then one could use subst (a*f, e, c) while if <b> is of the form e^(1/f) then one could use subst (a^f, e, c). The subst command also discerns the x^y in x^-y so that subst (a, sqrt(x), 1/sqrt(x)) yields 1/a. <a> and <b> may also be operators of an expression enclosed in double-quotes " or they may be function names. If one wishes to substitute for the independent variable in derivative forms then the at function (see below) should be used.

subst is an alias for substitute.

subst (<eq_1>, <expr>) or subst ([<eq_1>, ..., <eq_k>], <expr>) are other permissible forms. The <eq_i> are equations indicating substitutions to be made. For each equation, the right side will be substituted for the left in the expression <expr>.

exptsubst if true permits substitutions like y for %e^x in %e^(a*x) to take place.

When opsubst is false, subst will not attempt to substitute into the operator of an expression. E.g. (opsubst: false, subst (x^2, r, r+r[0])) will work.

Examples:

          (%i1) subst (a, x+y, x + (x+y)^2 + y);
                                              2
          (%o1)                      y + x + a
          (%i2) subst (-%i, %i, a + b*%i);
          (%o2)                       a - %i b

For further examples, do example (subst).

There are also some inexact matches for subst. Try ?? subst to see them.

(%o1)                                true
(%i2)