After a long hiatus I have come back to the issue of null tetrads in the physics package in light of the updates to  Maple in 2021. I have uploaded a document file to illustrate. See below. My first question concerns the labelling of elements of a null tetrad. After calling the metric 27,37 from Stephani et al, and using Setup to specify a null tetrad, Maple's choice is such that the elements labelled m and bar m are not complex. Rather, both these elements are in fact real, while the elements lablled l and n are complex, with one being the negative complex conjugate of the other. While these are just labels, they don't agree with the usual conventions for the Newman-Penrose formalism, which is disorienting. What convention is Maple using to label the elments of a null tetrad?

Next, I try to specify the null tetrad used by Stephani et al., first by converting it into covariant form (which I did by hand rather than in Maple). In Maple's default null tetrad, the order in which Maple listed the elements of the null tetrad is n, m, bar m, l (as rows in the matrix display for e_[ ]), so I followed that convention (in the conventions of Stephani et al., the first and fourh element should have scalar product -1, the second and third scalar product 1, and all other scalar products zero, which is the case). After entering the matrix and using Setup to specify the null tetrad by the matrix, I get an error message saying that the components of the metric with respect to my tetrad are not just 0, 1, and -1. Yet,  executing eta_[ ]  does not confirm this warning; nor does a computation by hand.

Finally, IsTetrad asserts the tetrad is not null, contrary to the fact that it is a null tetrad.

Since I have followed the conventions implicit in Maple's default null tetrad for this metric, I am puzzled as to what has gone wrong.SKMHH27_37_2021_New.mw

On the other hand, taking into account how Maple 2019 orders the coordinates in Stephani et al 27.37 and labels the null vectors in a null ttetrad, if I translate accordingly what I have in the 2021 Maple file, Maple 2019 confirms Stephani et al.'s null tetrad is indeed a null tetrad, as one would expect. See the following file.SKMHH27_37_2019_Var.mw.

Hello everybody.

My goal is to solve the following integro-functional equation:

(int(p^2/(f(p)-f(p+q)+omega), p = a .. b))/omega^2 = ln(omega^2+q^2)

(int(p^2/(f(p)-f(p+q)+omega), p = a .. b))/omega^2 = ln(omega^2+q^2)

where where is the unknown function and a, b are some numerical values as well as ω and q are real positive variables.

I would be grateful for any ideas.

Hello I cant sign in on my other MapleCloud account to view all my other Maple Documents. 

It says "Oops an error stopped us, from verifying your account. Please sign in again or continue using public MapleCloud features maple" Any suggestions on how to fix it? 

Streamlines, isotherms and microrotations for Re = 1, Pr = 7.2, Gr = 10⁵ and (a) Ha = 0 (b) Ha = 30 (c) Ha = 60 (d) Ha = 100.

for Ra = 10⁵, Ha = 50, Pr = 0.025 and θ = 1 − Y

eqat := {M . (D(theta))(0)+2.*Pr . f(0) = 0, diff(phi(eta), eta, eta)+2.*Sc . f(eta) . (diff(phi(eta), eta))-(1/2)*S . Sc . eta . (diff(phi(eta), eta))+N[t]/N[b] . (diff(theta(eta), eta, eta)) = 0, diff(g(eta), eta, eta)-2.*(diff(f(eta), eta)) . g(eta)+2.*f(eta) . (diff(g(eta), eta))-S . (g(eta)+(1/2)*eta . (diff(g(eta), eta)))-1/(sigma . Re[r]) . ((1+d^%H . exp(-eta))/(1+d . exp(-eta))) . g(eta)-beta^%H . ((1+d^%H . exp(-eta))^2/sqrt(1+d . exp(-eta))) . g(eta) . sqrt((diff(f(eta), eta))^2+g(eta)^2) = 0, diff(theta(eta), eta, eta)+2.*Pr . f(eta) . (diff(theta(eta), eta))-(1/2)*S . Pr . eta . (diff(theta(eta), eta))+N[b] . Pr . ((diff(theta(eta), eta)) . (diff(phi(eta), eta)))+N[t] . Pr . ((diff(theta(eta), eta))^2)+4/3 . N . (diff((C[T]+theta(eta))^3 . (diff(theta(eta), eta)), eta)) = 0, diff(f(eta), eta, eta, eta)-(diff(f(eta), eta))^2+2.*f(eta) . (diff(f(eta), eta))+g(eta)^2-S . (diff(f(eta), eta)+(1/2)*eta . (diff(f(eta), eta, eta)))-1/(sigma . Re[r]) . ((1+d^%H . exp(-eta))/(1+d . exp(-eta))) . (diff(f(eta), eta))-beta^%H . ((1+d^%H . exp(-eta))^2/sqrt(1+d . exp(-eta))) . (diff(f(eta), eta)) . sqrt((diff(f(eta), eta))^2+g(eta)^2) = 0, g(0) = 1, g(6) = 0, phi(0) = 1, phi(6) = 0, theta(0) = 1, theta(6) = 0, (D(f))(0) = 1, (D(f))(6) = 0};
sys1 := eval(eqat, {M = 0, N = 2, Pr = .8, S = -2.5, Sc = .5, d = 2, sigma = .2, C[T] = .5, N[b] = .4, N[t] = .4, Re[r] = 1.1, beta^%H = .2, d^%H = 1.5});
sys2 := eval(eqat, {M = 0, N = 2, Pr = .8, S = -2.5, Sc = .5, d = 2, sigma = .2, C[T] = .5, N[b] = .4, N[t] = .4, Re[r] = 1.1, beta^%H = .4, d^%H = 1.5});
sys3 := eval(eqat, {M = 0, N = 2, Pr = .8, S = -2.5, Sc = .5, d = 2, sigma = .2, C[T] = .5, N[b] = .4, N[t] = .4, Re[r] = 1.1, beta^%H = .6, d^%H = 1.5});
sys4 := eval(eqat, {M = 0, N = 2, Pr = .8, S = -2.5, Sc = .5, d = 2, sigma = .2, C[T] = .5, N[b] = .4, N[t] = .4, Re[r] = 1.1, beta^%H = .8, d^%H = 1.5});
sys5 := eval(eqat, {M = .5, N = 2, Pr = .8, S = -2.5, Sc = .5, d = 2, sigma = .2, C[T] = .5, N[b] = .4, N[t] = .4, Re[r] = 1.1, beta^%H = .2, d^%H = 1.5});
sys6 := eval(eqat, {M = .5, N = 2, Pr = .8, S = -2.5, Sc = .5, d = 2, sigma = .2, C[T] = .5, N[b] = .4, N[t] = .4, Re[r] = 1.1, beta^%H = .4, d^%H = 1.5});
sys7 := eval(eqat, {M = .5, N = 2, Pr = .8, S = -2.5, Sc = .5, d = 2, sigma = .2, C[T] = .5, N[b] = .4, N[t] = .4, Re[r] = 1.1, beta^%H = .6, d^%H = 1.5});
sys8 := eval(eqat, {M = .5, N = 2, Pr = .8, S = -2.5, Sc = .5, d = 2, sigma = .2, C[T] = .5, N[b] = .4, N[t] = .4, Re[r] = 1.1, beta^%H = .8, d^%H = 1.5});
sys9 := eval(eqat, {M = 1, N = 2, Pr = .8, S = -2.5, Sc = .5, d = 2, sigma = .2, C[T] = .5, N[b] = .4, N[t] = .4, Re[r] = 1.1, beta^%H = .2, d^%H = 1.5});
sys10 := eval(eqat, {M = 1, N = 2, Pr = .8, S = -2.5, Sc = .5, d = 2, sigma = .2, C[T] = .5, N[b] = .4, N[t] = .4, Re[r] = 1.1, beta^%H = .4, d^%H = 1.5});
sys11 := eval(eqat, {M = 1, N = 2, Pr = .8, S = -2.5, Sc = .5, d = 2, sigma = .2, C[T] = .5, N[b] = .4, N[t] = .4, Re[r] = 1.1, beta^%H = .6, d^%H = 1.5});
sys12 := eval(eqat, {M = 1, N = 2, Pr = .8, S = -2.5, Sc = .5, d = 2, sigma = .2, C[T] = .5, N[b] = .4, N[t] = .4, Re[r] = 1.1, beta^%H = .8, d^%H = 1.5});
sys13 := eval(eqat, {M = 1.5, N = 2, Pr = .8, S = -2.5, Sc = .5, d = 2, sigma = .2, C[T] = .5, N[b] = .4, N[t] = .4, Re[r] = 1.1, beta^%H = .2, d^%H = 1.5});
sys14 := eval(eqat, {M = 1.5, N = 2, Pr = .8, S = -2.5, Sc = .5, d = 2, sigma = .2, C[T] = .5, N[b] = .4, N[t] = .4, Re[r] = 1.1, beta^%H = .4, d^%H = 1.5});
sys15 := eval(eqat, {M = 1.5, N = 2, Pr = .8, S = -2.5, Sc = .5, d = 2, sigma = .2, C[T] = .5, N[b] = .4, N[t] = .4, Re[r] = 1.1, beta^%H = .6, d^%H = 1.5});
sys16 := eval(eqat, {M = 1.5, N = 2, Pr = .8, S = -2.5, Sc = .5, d = 2, sigma = .2, C[T] = .5, N[b] = .4, N[t] = .4, Re[r] = 1.1, beta^%H = .8, d^%H = 1.5});
 

Hi,

I ploted the step response of a MIMO system in Maple using DynamicSystems object.

The plot is incorrect.

What am I doing wrong?

Thanks for your help

I have a system described by 

I want to plot Y(s)/Z(s) = ((C . (1/((s . I) - A))) . B) + D with stepped inputs on both inputs

The system above evaluates to 

My commands are 

ss_a := A__m;
ss_b := B__m;
ss_c := C__m;
ss_d := D__m;
sys4 := StateSpace(ss_a, ss_b, ss_c, ss_d);
plots:-display([ResponsePlot(sys4, [Step(), Step()], 'duration' = 5, color = red)]);

Maple is returning the incorrect plot

The correct plot is 

SYSTEM

Correct plot

I would like to solve this system of PDEs along the x-interval [0,1] in three different subintervals: from 0 to 0.35, from 0.35 to 0.6, and from 0.6 to 1. I tried to solve the system by setting these same subintervals as you might see in my script, however it is now what I need. Any help would be very appreciated.

restart;
d1 := 0.05;
d2 := 0.3;
AA := 0.2;
BB := 0.1;
PDE1 := diff(u(x, t), t) = d1*diff(u(x, t), x, x) + w(x, t)*exp(AA*u(x, t) - BB*v(x, t));
PDE2 := diff(v(x, t), t) = d2*diff(v(x, t), x, x) - w(x, t)*exp(AA*u(x, t) - BB*v(x, t));
PDE3 := 0.0001*diff(w(x, t), t) = diff(w(x, t), x) - 0.8*x + 3.3;
IBC1 := u(0, t) = 1, u(1, t) = 0, u(x, 0) = piecewise(x < 0.35, -(4*x)*x + 1, 0.35 < x and x < 0.65, 1.32958 - 1.29167*x, 0.65 < x, 4*(x - 1)^2);
IBC2 := v(0, t) = 0, v(1, t) = 1, v(x, 0) = piecewise(x < 0.35, (4*x)*x + 1, 0.35 < x and x < 0.65, 1.32958 - 1.29167*x, 0.65 < x, -4*(x - 1)^2);
IBC3 := w(0, t) = 0.5, w(x, 0) = 1 - (0.3*x)*x;
pds := pdsolve([PDE1, PDE2, PDE3], [IBC1, IBC2, IBC3], numeric, time = t, range = 0 .. 1);
p1 := pds:-plot(t = 0, numpoints = 50);
p2 := pds:-plot(t = 1/8, numpoints = 50, color = blue);
p3 := pds:-plot(t = 1/4, numpoints = 50, color = green);

(Deleted because not reproducible on a different PC)

With 1D

With 2D

The root cause might be the same as for this open question.

int_warning_2D.mw

int_warning_1D.mw

How to insert pagebreak using code itself where I want as i run code 

As if I get more lines of output difficut to run through output give ctrl+Enter each place later 

Kind help

Hello,

 Can you tell me how I can create the variation tab of a function with Maple 2022?

Thanking you,
 
,DAVID CRESPIL

When exporting a maple file containing

pH = 1/2*(pKa - log[10](c)),

I could see that the minus was transformed into a K

Any idea for solving this problem ?

Cheers for Maple anyway

restart;

OdeSys := diff(U(Y), Y, Y)+Theta(Y)+N*(Theta(Y)*Theta(Y))-(M*M)*U(Y) = 0, diff(Theta(Y), Y, Y)+E*(diff(U(Y), Y))^2 = 0;

Cond := U(0) = lambda*(D(U))(0), Theta(0) = A+g*(D(Theta))(0), U(1) = 0, Theta(1) = B; sys := [OdeSys, Cond];
Ans := dsolve(sys);

in my program, I keep assumptions in a set. Sometimes this is empty if no assumptions are used. This never caused a problem before (at least I do not think so, else I would have seen it) when using empty {} in assuming, except for now.

Here is one example below. Is this a known problem? I noticed when changing {} to [] the error goes away. I am not sure why, and if this is known issue. But will change from a set to a list to avoid this. 

Maple 2022.2 on windows 10

Download feb_14_2023.mw

My question is can the last step be equal to 1/6.

I want to output to 1/6. it outputs to sqrt(9)/18 - (See Below).

Download limit-sqrt-5.mw

My Maple Program run perfectly  with Window 10.  My new Laptop has Window 11 and I get system  crash wenn I applied

plot3d(...) .

So I think It is somethink with the Grapics Redering ?

Can somebody help ?

Betriebsystemname    Microsoft Windows 11 Home
Version    10.0.22621 Build 22621
Weitere Betriebsystembeschreibung     Nicht verfügbar
Betriebsystemhersteller    Microsoft Corporation
Systemname    ELIPAN
Systemhersteller    SAMSUNG ELECTRONICS CO., LTD.
Systemmodell    750XED
Systemtyp    x64-basierter PC
System-SKU    SCAI-A5A5-A5A5-ADLP-PCFG
Prozessor    12th Gen Intel(R) Core(TM) i5-1235U, 1300 MHz, 10 Kern(e), 12 logische(r) Prozessor(en)
BIOS-Version/-Datum    American Megatrends International, LLC. P08CFG.033.220913.HQ, 13.09.2022
SMBIOS-Version    3.4
Version des eingebetteten Controllers    255.255
BIOS-Modus    UEFI
BaseBoard-Hersteller    SAMSUNG ELECTRONICS CO., LTD.
BaseBoard-Produkt    NP750XED-KC5DE
BaseBoard-Version    SAMSUNG_SW_REVISION_12345+10.0.22000
Plattformrolle    Mobil
Sicherer Startzustand    Ein
PCR7-Konfiguration    Erweiterung zum Anzeigen erforderlich
Windows-Verzeichnis    C:\WINDOWS
Systemverzeichnis    C:\WINDOWS\system32
Startgerät    \Device\HarddiskVolume1
Gebietsschema    Deutschland
Hardwareabstraktionsebene    Version = "10.0.22621.819"
Benutzername    ELIPAN\Pan
Zeitzone    Mitteleuropäische Zeit
Installierter physischer Speicher (RAM)    16,0 GB
Gesamter physischer Speicher    15,7 GB
Verfügbarer physischer Speicher    8,28 GB
Gesamter virtueller Speicher    16,7 GB
Verfügbarer virtueller Speicher    6,98 GB
Größe der Auslagerungsdatei    1,00 GB
Auslagerungsdatei    C:\pagefile.sys
Kernel-DMA-Schutz    Ein
Virtualisierungsbasierte Sicherheit    Wird ausgeführt...
Virtualisierungsbasierte Sicherheit – erforderliche Sicherheitseigenschaften    
Virtualisierungsbasierte Sicherheit – verfügbare Sicherheitseigenschaften    Allgemeine Virtualisierungsunterstützung, Sicherer Start, DMA-Schutz, UEFI-Code Readonly, SMM Security Mitigations 1.0, Modusbasierte Ausführungssteuerung, APIC-Virtualisierung
Virtualisierungsbasierte Sicherheit – konfigurierte Dienste    Durch Hypervisor erzwungene Codeintegrität
Virtualisierungsbasierte Sicherheit – ausgeführte Dienste    Durch Hypervisor erzwungene Codeintegrität
Windows Defender-Anwendungssteuerungsrichtlinie    Erzwungen
Windows Defender-Anwendungssteuerungs-Richtlinie für den Benutzermodus    Aus
Unterstützung der Geräteverschlüsselung    Erweiterung zum Anzeigen erforderlich
Es wurde ein Hypervisor erkannt. Features, die für Hyper-V erforderlich sind, werden nicht angezeigt.    

IndependencePolynomial returns the independence polynomial for the graph G in the variable x.

For the following example, its calculation took over 20 minutes and still hasn't produced a result, and what's fatal is that it  has consumed 4G  memory.

with(GraphTheory):
G:=ConvertGraph("W|tNHEpCKoh`@@Po_WHB@CKC?WGO{G?KKCB`?OMG?_y_?Sn");
G1:=LineGraph(G);
IndependencePolynomial(G1, x) # be careful

I use  codes in  the link https://github.com/pernici/hobj.

It produced results quickly (It takes approximately 5 seconds.). So I think the built-in function " IndependencePolynomial " should be able to be improved. (Of course we are usually very concerned about their coefficients) 

Their coefficients of the independent polynomial of G1 are as follows.

[340649, 12329124, 68797662, 140606548, 139481127, 77027880, 25546428, 5303544, 700911, 58580, 2982, 84, 1]

It tells me the total number of independence sets with size 12 is 340649.