Combining terms of the same type

The combine command joins subexpressions of various types.

combine takes two arguments:
- expr, an expression.
- function, the name of a function or class of functions. function can be one of exp, log, ln, sin, cos, or trig.
combine(expr,function) returns the expression with subexpressions corresponding to the second argument combined.

The combine command can duplicate the effect of other commands.

combine(expr,ln) or combine(expr,log) gives the same result as lncollect(expr) (see Section 10.3.5).
combine(expr,trig) or combine(expr,sin) or combine(expr,cos) gives the same result as tcollect(expr) (see Section 10.2.4).

combine(exp(x)*exp(y)+sin(x)*cos(x)+ln(x)+ln(y),exp)

cosx sinx+lnx+lny+e^x+y

combine(exp(x)*exp(y)+sin(x)*cos(x)+ln(x)+ln(y),trig)

or:

combine(exp(x)*exp(y)+sin(x)*cos(x)+ln(x)+ln(y),sin)

or:

combine(exp(x)*exp(y)+sin(x)*cos(x)+ln(x)+ln(y),cos)

e^x e^y+lnx+lny+

sin

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2 x

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combine(exp(x)*exp(y)+sin(x)*cos(x)+ln(x)+ln(y),ln)

or:

combine(exp(x)*exp(y)+sin(x)*cos(x)+ln(x)+ln(y),log)

cosx sinx+e^x e^y+ln

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⎝

x y

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