Hello! I try to make friends physics package and matrixes. But I am faced with difficulties. To be more specific, to consider a code:

with(Physics):
Setup(mathematicalnotation = true);
Coordinates(X);
Setup(tensors = A[mu](X));
PDEtools:-declare(A(X), p0(X), pm(X), pp(X), pt(X), U(X), m5(X))

And then I create a matrix:

pt := proc (X) options operator, arrow; Matrix(2, 2, [[p0(X), sqrt(2)*pp(X)], [sqrt(2)*pm(X), -p0(X)]]) end proc;

It displays as:

Why do p0, pp, pm become function only one variable x1?

Interestingly that maple understands the next matrix:

Nevertheless even for function only one variable derivative works fine:

And I can construct more complicated functions:

But why is only one variable?

Hi! I have a variable polynomial expression and I want to cut off all the terms of order 3 and more, for every product of variables.

For example consider the polynomial P = x + y + a*x^2 + b*x^3 + c*x*y + d*x^2*y + e*x*y^2 + y^2, I want an operation who returns me a*x^2 + c*x*y + y^2

(terms for which the sum of exponents in x and y exceeds or less two are being deleted)

Is it possible?

I attempt to understand is it possible whether to calculate the next expression by means of mathematica:

where

{,}- anti-communicator;

 a=0,1,2,3;

\tau^{0}-unity matrix; \tau^{i} - Pauli matrix;

and:
 

 
finally - Levi-Civita symbol; -Hermitian conjugation.

Thank you for your kind replies .

I need hepl.  I work with the physics paсkage and I set:

with(Physics);
with(StandardModel);
Setup(mathematicalnotation = true)

Coordinates(X)

Define(p)

Setup(su2)

CompactDisplay(p(X))

U := 1+i*(1/f)*p[a](X)*Psigma[a]

H := v*U

DD[mu] := (d_[mu]+2*i*nu_5*KroneckerDelta[mu, 0])*Psigma[0]

And next:

Trace(DD[mu]*H*DD[mu]*H) or simplify(DD[mu]*H*DD[mu]*H)

Maple speaks:

Error, (in Physics:-Trace) invalid input: `union` received Physics:-d_[mu] = F1, which is not valid for its 1st argument

What I am doing wrong? (f, v, nu_5 is constans; a=1,2,3 and mu=0,1,2,3, Psigma[0] is unit matrix 2x2)

And if I write:

simplify(Trace(Psigma[a]*Psigma[a]))

Maple doesn't understand that it equals six. 

I need yours hepl.  I work with the physics paсkage and I set:

with(Physics)

Setup(mathematicalnotation = true)

 Coordinates(X)

Setup(Dgammarepresentation = standard)

Setup(spaceindices = uppercaselatin)

Define(m, m5, y, p, mm, pp)

I try to square the next value: 

W := Dgamma[mu]*d_[mu]+M+Psigma[A]*aa[A]-mm*Dgamma[0]-m5*Dgamma[0]*Dgamma[5]+I*Dgamma[5]*Psigma[B]*pp[B]+I*Dgamma[5]*y

("*" is multiplication)

W*W

And after that I want to simplify it:

Simplify(W*W)

I guess that matter is owing to d_[`~mu`]. If I remove this term:

E:=Psigma[A]*aa[A]-mm*Dgamma[0]-m5*Dgamma[0]*Dgamma[5]+I*Dgamma[5]*Psigma[B]*pp[B]+I*Dgamma[5]*y

And if i do:

E*E

Then next error emerges:

What is it?