Symbolic Math Toolbox

compose

Functional composition

Syntax

• compose(f,g)
  compose(f,g,z)
  compose(f,g,x,z)
  compose(f,g,x,y,z)
  

Description

compose(f,g) returns f(g(y)) where f = f(x) and g = g(y). Here x is the symbolic variable of f as defined by findsym and y is the symbolic variable of g as defined by findsym.

compose(f,g,z) returns f(g(z)) where f = f(x), g = g(y), and x and y are the symbolic variables of f and g as defined by findsym.

compose(f,g,x,z) returns f(g(z)) and makes x the independent variable for f. That is, if f = cos(x/t), then compose(f,g,x,z) returns cos(g(z)/t) whereas compose(f,g,t,z) returns cos(x/g(z)).

compose(f,g,x,y,z) returns f(g(z)) and makes x the independent variable for f and y the independent variable for g. For f = cos(x/t) and
g = sin(y/u), compose(f,g,x,y,z) returns cos(sin(z/u)/t) whereas compose(f,g,x,u,z) returns cos(sin(y/z)/t).

Examples

Suppose

• syms x y z t u;
  f = 1/(1 + x^2); g = sin(y); h = x^t; p = exp(-y/u);
  

Then

• compose(f,g)       ->  1/(1+sin(y)^2) 
  compose(f,g,t)     ->  1/(1+sin(t)^2)
  compose(h,g,x,z)   ->  sin(z)^t
  compose(h,g,t,z)   ->  x^sin(z)
  compose(h,p,x,y,z) ->  exp(-z/u)^t 
  compose(h,p,t,u,z) ->  x^exp(-y/z) 
  

See Also

finverse, subs, syms

colspace

conj