## 398 Reputation

4 years, 327 days

## Physics differentialoperators...

Hi,

A possible way is to define a formal differential operator within the Physics package. It can be define with an arbitrary function and trigged at will. For an exemple, have look at:

https://www.mapleprimes.com/posts/208710-Quantum-Commutation-Rules-Basics

## Component...

Hi,

Using "Component", it is possible to reconstruct a Vector:

V := Vector([seq(Component(q_, k), k = 1 .. 3)])

Component2Vector.mw

## Parentheses...

Try -3 - (-5) or  4*(-10), It should work as expected.

However, I agree that an expression like -3 - -5 should work without parentheses in Maple, mathematically the expression is correct, surprising. Entering -3-+-5 or 4*-10 in Matlab gives the expected result.

## Alias and Physics:-Latex...

Hi,

I think that using the new Physics:-Latex with alias, there is even no need for replacing.

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 (2)
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 x \left( t \right) ={\it \_C1}\,{{\rm e}^{t}}+{\it \_C2}\,{{\rm e}^{-{ \frac {t}{2}}}}\sin \left( {\frac {\sqrt {3}t}{2}} \right) +{\it \_C3} \,{{\rm e}^{-{\frac {t}{2}}}}\cos \left( {\frac {\sqrt {3}t}{2}}  \right)
 >
 x \left(t \right) = c_{1} {\rm e}^{t}+c_{2} {\rm e}^{-\frac{t}{2}} \sin \left(\frac{\sqrt{3} t}{2}\right)+c_{3} {\rm e}^{-\frac{t}{2}} \cos \left(\frac{\sqrt{3} t}{2}\right)
 >

Hi,

## Differential operator...

You might define a differential operator

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 (1)
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 (2)
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 (3)
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 (4)
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 (5)
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 (6)
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## Setup(quantumoperators = V)...

Hi,

With Physics package, to get this feature, V should be declared as a quantum operator. Also, use Dagger instead of Transpose, or V_^*.

restart;
with(Physics);
with(Physics[Vectors]);
Setup(quantumoperators = V);
V_*Dagger(V_);

This question is related:

Hi,

L := [1, 2, 3, 4, 5];
L := [1, 2, 3, 4, 5]

15

## Restart...

Hi,

I have the same sometime. Just enter "restart" and this should load the last version, even if the message is the same. Otherwise, just close your worksheet and reopen it, it should work fine.

## Several ways...

Hi,

There are several ways. You can use "indets" to extract the variable of an expression, and then "select" according particular properties. For instance, assuming x and y have a t depedency, while A and B are independent of that parameter:

EE := (x(t)/A)^2 + (y(t)/B)^2 = 1;
2       2
x(t)    y(t)
EE := ----- + ----- = 1
2       2
A       B

FF := indets(EE);
FF := {A, B, t, x(t), y(t)}

select(u -> type(u, freeof(t)), FF);
{A, B}

## Close the Palette...

Hi,

In addition to Edgardo's recommendations, you could try to close the palettes (left Panel). There is a known issue at startup for Maple 2020 involving those palettes. Once Maple has started again, you can reopen the required palettes.

## LinearAlgebra:-Trace...

Hi,

The LinearAlgebra algebra package has a trace function.

Either enter:

LinearAlgebra:-Trace(J)

with(LinearAlgebra):

Trace(J)

Note, there is also a Trace function within the Physics package. In addition to standard Matrix, it can work on special matrices such as the Pauli or the Dirac matrices.

## Functional derivative...

Hi,

Functional derivative, that is derivative of a function with respect to another one, is supported within the Physics package. For instance:

restart;
with(Physics):
ee := diff(f(t), t)^2;
2
/ d      \
ee := |--- f(t)|
\ dt     /

diff(ee, diff(f(t), t));
/ d      \
2 |--- f(t)|
\ dt     /

In your code, just add "with(Physics):" after restart, and there will be no error message anymore.

You could also have a look at the Fundiff function. Enter ?Physics:-Fundiff

## whattype...

Hi,

Entering whattype(a) will return "set".

## Hi, maybe CodeTools:-ProgramAnalysis:-St...

Hi, maybe CodeTools:-ProgramAnalysis:-StaticCallGraph might be helpful. This is new to Maple 2020.

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