## 40 Reputation

8 years, 139 days

## How to refer to previous result?...

Maple 2015

I want to reference the previous equation/expression which is not displayed (':')in my worksheet. I allready know the '%' sign, but this references the previous equation/expression which was executed . By previous I mean the result (which is not displayed) in the previous line.

As I do not want the previous equation to be displayed I also cannot use the equation lable (CTRL+L).

Example

x:=a=b+1:

solve(previous,{b});

## Using partial derivatives as operators...

Maple 2015

Hi,

I am trying to calculate the commutator $[v,w]:=vw-wv$.

For the sake of simplicity lets say

$$v=\dfrac{\partial}{\partial x}$$
and

$$w=x\dfrac{\partial}{\partial t}$$

I know how to calculate the commutator by hand, but I would like to learn how I can do these kind of calculations with maple.

**In this example the calculations by hand look like:**

$$[v,w]=\dfrac{\partial}{\partial x}\left( x\dfrac{\partial}{\partial t}\right)-x\dfrac{\partial}{\partial t}\dfrac{\partial}{\partial x}$$
$$=\dfrac{\partial}{\partial t}+x\dfrac{\partial^2}{\partial x \partial t}-x\dfrac{\partial^2}{\partial t \partial x}=\dfrac{\partial}{\partial t}$$

How can I "teach" maple to do this?

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