Maple Questions and Posts

Unable to accurately solve an ODE BVP with delay t...

Asked by: sursumCorda 922

September 10 2023

1 0

Delay differential equations in Chebfun lists 15 examples "taken from the literature". Many of them can be (numerically) solved in Maple without difficulty, yet when I attempt to solve the in the above link, Maple's internal solver `dsolve/numeric` just halts with an error.

plots:-odeplot(dsolve({D(u)(t) + u(t)**2 + 2*u(1/2*t) = 1/2*exp(t), u(0) = u(1/3)}, type = numeric, range = 0 .. 1/3), size = ["default", "golden"]);
Error, (in dsolve/numeric) delay equations are not supported for bvp solvers

Even if I guess an initial (or final) value artificially, the solution is still less reliable (For instance, what is the approximate endpoint value? 0.26344 or 0.2668?):

restart;
dde := D(u)(t) + u(t)**2 + u(t/2)*2 = exp(t)/2:
x__0 := 2668/10000:
sol0 := dsolve([dde, u(0) = x__0], type = numeric, 'delaymax' = 1/6, range = 0 .. 1/3):
plots['odeplot'](sol0, [[t, u(t)], [t, x__0]], 'size' = ["default", "golden"]);

x__1 := 26344/100000:
sol1 := dsolve([dde, u(1/3) = x__1], type = numeric, 'delaymax' = 1/6, range = 0 .. 1/3):
plots['odeplot'](sol1, [[t, u(t)], [t, x__1]], size = ["default", "golden"]);

Compare: (Note that the reference numerical solution implies that its minimum should be no less than 0.258 (Is this incorrect?).).

And actually, the only known constraint is simply u(0)＝u(⅓) (so neither value is known beforehand). Can Maple process this boundary condition automatically (that is, without the need for manual preprocessing and in absence of any other prior information)?
I have read the help page How to | Numeric Delay Differential Equations and Numerical Solution of Difficult ODE Boundary Value Problems, but it appears that those techniques are more or less ineffective here. So, how do I solve such a "first order nonlinear 'BVP' with pantograph delay" in Maple?

how to include describe (sin)...

Asked by: Carolyn Davis 15

September 09 2023

2 2

I'm unsure how to fix the error with sin, the help guide suggests using the command Describe (Sin)

>

#Clear memory.
restart;

#Initialise variables and arrays.
h:=((pi/20)^2);
n:=15;
k:=0.1;
m:=10;
t:=Array(0..m):
x:=Array(0..n):
u:=Array(0..n,0..m):

#Initialise the x array and the initial u(x,0) boundary.
   for i from 0 to n do
x[i]:=i*h;
u[i,0]:=x[i];
end do:

#Initialise the t array and the u(x,t)side boundaries.
  for j from 0 to m do
t[j]:=j*k;
u[0,j]:=0;
u[n,j]:=pi/2;
end do:

#Use the 2D explicit finite difference method.
for j from 0 to m-1 do
    for i from 1 to n-1 do
      u[i,j+1]:=(400*u[i-1,j]-400*u[i,j]+400*u[i+1,j]+1)/(pi^2)*(4*sin(2*x));
  end do;
end do:

#Display the u(x,t) values.
printf("2D Explicit Finite Difference Method\n");
printf("------------------------------------\n");
printf(" x\t\t t\t\t u\n");
for i from 0 to n do
    printf("% 9.4f\t% 9.4f\t% 9.4f\n",x[i],t[m],u[i,m]);
end do;

(1/400)*pi^2

Error, invalid input: sin expects its 1st argument, x, to be of type algebraic, but received Array(0..15, [0,1/200*pi^2,1/100*pi^2,3/200*pi^2,1/50*pi^2,1/40*pi^2,3/100*pi^2,7/200*pi^2,1/25*pi^2,9/200*pi^2,1/20*pi^2,11/200*pi^2,3/50*pi^2,13/200*pi^2,7/100*pi^2,3/40*pi^2])

2D Explicit Finite Difference Method
------------------------------------
x t u
0.0000 1.0000 0.0000

Error, (in fprintf) number expected for floating point format

>

Download Asst_2_Q3bcd.mw

How do I fix the (fprintf) number expected for flo...

Asked by: Carolyn Davis 15

September 09 2023

1 2

>

#Clear memory.
restart;

#Initialise variables and arrays.
h:=0.1;
n:=10;
x:=Array(0..n):
y:=Array(0..n):
x[0]:=0;
y[0]:=2;
yd:=-1;

#Initialise the x array.
for i from 1 to n do
    x[i]:=x[0]+i*h;
end do:

#Calculate the first y value.
y[1]:=(203*y[0]-22*yd+4)/220:

#Calculate the remaining y values.
for i from 1 to n-1 do
    y[i+1]:=203*y[i]-110*y[i-1]+4*exp^(-3*x[i])/110;
end do:

#Display the x and y arrays.
printf("1D Explicit Finite Difference Method\n");
printf("------------------------------------\n");
printf("x\t\ty\n");
for i from 0 to n do
     printf("%f\t %f\n",x[i],y[i]);
end do;

>

1D Explicit Finite Difference Method
------------------------------------
x                y
0.000000         2.000000
0.100000         1.963636
0.200000

Error, (in fprintf) number expected for floating point format

>

Download Asst_2_Q1c.mw

I dont understand the cause of this error, can anyone please assist?

How to Check if one Interval is a Subset of Anothe...

Asked by: DJJerome1976 535

September 09 2023

1 4

Hi,

I am trying to write a procedure that takes two intervals of real numbers (in interval notation) and checks if one is a subset of the other. For example, isSubset([-5,2],[-10,infinity)) would return true, but isSubset([-5,2],(-5,infinity)) would return false. Any idea how to go about this? I am having difficulty knowing where to start.

Thanks!

collect all terms u(, , index) with similar index ...

Asked by: Zeineb 520

September 09 2023

0 1

Dear all

I have an equation, I would like to collect or regroup all similar terms

MCode.mw

Thank you

Matrice Plotting...

Asked by: kjell 40

September 09 2023

0 2

Hello!!

Matrice: (x,y)=(-2,-3),(-1,2),(3,4),(1,-2)

When plotting 3 lines with points are ok, but the fourth line os missing! All 4 points are there

How to include the 4th line?

Kjell

Determine if a nested list is completely rectangul...

Asked by: sursumCorda 922

September 09 2023

2 4

For instance, “[1, 2, 3]”, “[``([1, 2]), uneval([3])]”, and “[[1, 2], [3, 'NULL']]” are fully rectangular. “[1, 2, [3]]”, “[`[]`(1, 2), [3]]”, and “[[1, 2], [3, NULL]]” are considered nonrectangular, but if we temporarily freeze the "ragged" parts or regard them as a depth-1 container, the corresponding expressions will seem rectangular. `type(…, list(Non(list)))` and `type(…, listlist(Non(list)))` check these, but they do not work for general cases.
To be specific, the desired output should be something like

IsRectangular([[[l, 2], [3, 4]], [[5, 6], [7, 8]]]);
 = 
                            true, 3

IsRectangular([[[O, l, 2], [3, 4]], [[5, 6], [7, 8]]]);
 = 
                            false, 2

IsRectangular([[[[l], 2], [3, 4]], [[5, 6], [7, 8]]], 3);
 = 
                            true, 3

IsRectangular([[O, [l, 2], [3, 4]], [[5, 6], [7, 8]]], 2);
 = 
                            false, 1

The results above can be obtained by some observations. However, if the input has deeper levels, evaluating this will be a punishing work:

test__1 := [[[[[[[[-288],[-287],[-286]],[[-285],[-284],[-283]],[[-282],[-281],[-280]],[[-279],[-278],[-277]]]],[[[[-276],[-275],[-274]],[[-273],[-272],[-271]],[[-270],[-269],[-268]],[[-267],[-266],[-265]]]],[[[[-264],[-263],[-262]],[[-261],[-260],[-259]],[[-258],[-257],[-256]],[[-255],[-254],[-253]]]]],[[[[[-252],[-251],[-250]],[[-249],[-248],[-247]],[[-246],[-245],[-244]],[[-243],[-242],[-241]]]],[[[[-240],[-239],[-238]],[[-237],[-236],[-235]],[[-234],[-233],[-232]],[[-231],[-230],[-229]]]],[[[[-228],[-227],[-226]],[[-225],[-224],[-223]],[[-222],[-221],[-220]],[[-219],[-218],[-217]]]]]],[[[[[[-216],[-215],[-214]],[[-213],[-212],[-211]],[[-210],[-209],[-208]],[[-207],[-206],[-205]]]],[[[[-204],[-203],[-202]],[[-201],[-200],[-199]],[[-198],[-197],[-196]],[[-195],[-194],[-193]]]],[[[[-192],[-191],[-190]],[[-189],[-188],[-187]],[[-186],[-185],[-184]],[[-183],[-182],[-181]]]]],[[[[[-180],[-179],[-178]],[[-177],[-176],[-175]],[[-174],[-173],[-172]],[[-171],[-170],[-169]]]],[[[[-168],[-167],[-166]],[[-165],[-164],[-163]],[[-162],[-161],[-160]],[[-159],[-158],[-157]]]],[[[[-156],[-155],[-154]],[[-153],[-152],[-151]],[[-150],[-149],[-148]],[[-147],[-146],[-145]]]]]],[[[[[[-144],[-143],[-142]],[[-141],[-140],[-139]],[[-138],[-137],[-136]],[[-135],[-134],[-133]]]],[[[[-132],[-131],[-130]],[[-129],[-128],[-127]],[[-126],[-125],[-124]],[[-123],[-122],[-121]]]],[[[[-120],[-119],[-118]],[[-117],[-116],[-115]],[[-114],[-113],[-112]],[[-111],[-110],[-109]]]]],[[[[[-108],[-107],[-106]],[[-105],[-104],[-103]],[[-102],[-101],[-100]],[[-99],[-98],[-97]]]],[[[[-96],[-95],[-94]],[[-93],[-92],[-91]],[[-90],[-89],[-88]],[[-87],[-86],[-85]]]],[[[[-84],[-83],[-82]],[[-81],[-80],[-79]],[[-78],[-77],[-76]],[[-75],[-74],[-73]]]]]],[[[[[[-72],[-71],[-70]],[[-69],[-68],[-67]],[[-66],[-65],[-64]],[[-63],[-62],[-61]]]],[[[[-60],[-59],[-58]],[[-57],[-56],[-55]],[[-54],[-53],[-52]],[[-51],[-50],[-49]]]],[[[[-48],[-47],[-46]],[[-45],[-44],[-43]],[[-42],[-41],[-40]],[[-39],[-38],[-37]]]]],[[[[[-36],[-35],[-34]],[[-33],[-32],[-31]],[[-30],[-29],[-28]],[[-27],[-26],[-25]]]],[[[[-24],[-23],[-22]],[[-21],[-20],[-19]],[[-18],[-17],[-16]],[[-15],[-14],[-13]]]],[[[[-12],[-11],[-10]],[[-9],[-8],[-7]],[[-6],[-5],[-4]],[[-3],[-2],[-1],[-0]]]]]]],[[[[[[[0],[1],[2]],[[3],[4],[5]],[[6],[7],[8]],[[9],[10],[11]]]],[[[[12],[13],[14]],[[15],[16],[17]],[[18],[19],[20]],[[21],[22],[23]]]],[[[[24],[25],[26]],[[27],[28],[29]],[[30],[31],[32]],[[33],[34],[35]]]]],[[[[[36],[37],[38]],[[39],[40],[41]],[[42],[43],[44]],[[45],[46],[47]]]],[[[[48],[49],[50]],[[51],[52],[53]],[[54],[55],[56]],[[57],[58],[59]]]],[[[[60],[61],[62]],[[63],[64],[65]],[[66],[67],[68]],[[69],[70],[71]]]]]],[[[[[[72],[73],[74]],[[75],[76],[77]],[[78],[79],[80]],[[81],[82],[83]]]],[[[[84],[85],[86]],[[87],[88],[89]],[[90],[91],[92]],[[93],[94],[95]]]],[[[[96],[97],[98]],[[99],[100],[101]],[[102],[103],[104]],[[105],[106],[107]]]]],[[[[[108],[109],[110]],[[111],[112],[113]],[[114],[115],[116]],[[117],[118],[119]]]],[[[[120],[121],[122]],[[123],[124],[125]],[[126],[127],[128]],[[129],[130],[131]]]],[[[[132],[133],[134]],[[135],[136],[137]],[[138],[139],[140]],[[141],[142],[143]]]]]],[[[[[[144],[145],[146]],[[147],[148],[149]],[[150],[151],[152]],[[153],[154],[155]]]],[[[[156],[157],[158]],[[159],[160],[161]],[[162],[163],[164]],[[165],[166],[167]]]],[[[[168],[169],[170]],[[171],[172],[173]],[[174],[175],[176]],[[177],[178],[179]]]]],[[[[[180],[181],[182]],[[183],[184],[185]],[[186],[187],[188]],[[189],[190],[191]]]],[[[[192],[193],[194]],[[195],[196],[197]],[[198],[199],[200]],[[201],[202],[203]]]],[[[[204],[205],[206]],[[207],[208],[209]],[[210],[211],[212]],[[213],[214],[215]]]]]],[[[[[[216],[217],[218]],[[219],[220],[221]],[[222],[223],[224]],[[225],[226],[227]]]],[[[[228],[229],[230]],[[231],[232],[233]],[[234],[235],[236]],[[237],[238],[239]]]],[[[[240],[241],[242]],[[243],[244],[245]],[[246],[247],[248]],[[249],[250],[251]]]]],[[[[[252],[253],[254]],[[255],[256],[257]],[[258],[259],[260]],[[261],[262],[263]]]],[[[[264],[265],[266]],[[267],[268],[269]],[[270],[271],[272]],[[273],[274],[275]]]],[[[[276],[277],[278]],[[279],[280],[281]],[[282],[283],[284]],[[285],[286],[287]]]]]]]]:
test__2 := [[[[[[[[-288],[-287],[-286]],[[-285],[-284],[-283]],[[-282],[-281],[-280]],[[-279],[-278],[-277]]]],[[[[-276],[-275],[-274]],[[-273],[-272],[-271]],[[-270],[-269],[-268]],[[-267],[-266],[-265]]]],[[[[-264],[-263],[-262]],[[-261],[-260],[-259]],[[-258],[-257],[-256]],[[-255],[-254],[-253]]]]],[[[[[-252],[-251],[-250]],[[-249],[-248],[-247]],[[-246],[-245],[-244]],[[-243],[-242],[-241]]]],[[[[-240],[-239],[-238]],[[-237],[-236],[-235]],[[-234],[-233],[-232]],[[-231],[-230],[-229]]]],[[[[-228],[-227],[-226]],[[-225],[-224],[-223]],[[-222],[-221],[-220]],[[-219],[-218],[-217]]]]]],[[[[[[-216],[-215],[-214]],[[-213],[-212],[-211]],[[-210],[-209],[-208]],[[-207],[-206],[-205]]]],[[[[-204],[-203],[-202]],[[-201],[-200],[-199]],[[-198],[-197],[-196]],[[-195],[-194],[-193]]]],[[[[-192],[-191],[-190]],[[-189],[-188],[-187]],[[-186],[-185],[-184]],[[-183],[-182],[-181]]]]],[[[[[-180],[-179],[-178]],[[-177],[-176],[-175]],[[-174],[-173],[-172]],[[-171],[-170],[-169]]]],[[[[-168],[-167],[-166]],[[-165],[-164],[-163]],[[-162],[-161],[-160]],[[-159],[-158],[-157]]]],[[[[-156],[-155],[-154]],[[-153],[-152],[-151]],[[-150],[-149],[-148]],[[-147],[-146],[-145]]]]]],[[[[[[-144],[-143],[-142]],[[-141],[-140],[-139]],[[-138],[-137],[-136]],[[-135],[-134],[-133]]]],[[[[-132],[-131],[-130]],[[-129],[-128],[-127]],[[-126],[-125],[-124]],[[-123],[-122],[-121]]]],[[[[-120],[-119],[-118]],[[-117],[-116],[-115]],[[-114],[-113],[-112]],[[-111],[-110],[-109]]]]],[[[[[-108],[-107],[-106]],[[-105],[-104],[-103]],[[-102],[-101],[-100]],[[-99],[-98],[-97]]]],[[[[-96],[-95],[-94]],[[-93],[-92],[-91]],[[-90],[-89],[-88]],[[-87],[-86],[-85]]]],[[[[-84],[-83],[-82]],[[-81],[-80],[-79]],[[-78],[-77],[-76]],[[-75],[-74],[-73]]]]]],[[[[[[-72],[-71],[-70]],[[-69],[-68],[-67]],[[-66],[-65],[-64]],[[-63],[-62],[-61]]]],[[[[-60],[-59],[-58]],[[-57],[-56],[-55]],[[-54],[-53],[-52]],[[-51],[-50],[-49]]]],[[[[-48],[-47],[-46]],[[-45],[-44],[-43]],[[-42],[-41],[-40]],[[-39],[-38],[-37]]]]],[[[[[-36],[-35],[-34]],[[-33],[-32],[-31]],[[-30],[-29],[-28]],[[-27],[-26],[-25]]]],[[[[-24],[-23],[-22]],[[-21],[-20],[-19]],[[-18],[-17],[-16]],[[-15],[-14],[-13]]]],[[[[-12],[-11],[-10]],[[-9],[-8],[-7]],[[-6],[-5],[-4]],[[-3],[-2,0],[-0]]]]]]],[[[[[[[-1],[1],[2]],[[3],[4],[5]],[[6],[7],[8]],[[9],[10],[11]]]],[[[[12],[13],[14]],[[15],[16],[17]],[[18],[19],[20]],[[21],[22],[23]]]],[[[[24],[25],[26]],[[27],[28],[29]],[[30],[31],[32]],[[33],[34],[35]]]]],[[[[[36],[37],[38]],[[39],[40],[41]],[[42],[43],[44]],[[45],[46],[47]]]],[[[[48],[49],[50]],[[51],[52],[53]],[[54],[55],[56]],[[57],[58],[59]]]],[[[[60],[61],[62]],[[63],[64],[65]],[[66],[67],[68]],[[69],[70],[71]]]]]],[[[[[[72],[73],[74]],[[75],[76],[77]],[[78],[79],[80]],[[81],[82],[83]]]],[[[[84],[85],[86]],[[87],[88],[89]],[[90],[91],[92]],[[93],[94],[95]]]],[[[[96],[97],[98]],[[99],[100],[101]],[[102],[103],[104]],[[105],[106],[107]]]]],[[[[[108],[109],[110]],[[111],[112],[113]],[[114],[115],[116]],[[117],[118],[119]]]],[[[[120],[121],[122]],[[123],[124],[125]],[[126],[127],[128]],[[129],[130],[131]]]],[[[[132],[133],[134]],[[135],[136],[137]],[[138],[139],[140]],[[141],[142],[143]]]]]],[[[[[[144],[145],[146]],[[147],[148],[149]],[[150],[151],[152]],[[153],[154],[155]]]],[[[[156],[157],[158]],[[159],[160],[161]],[[162],[163],[164]],[[165],[166],[167]]]],[[[[168],[169],[170]],[[171],[172],[173]],[[174],[175],[176]],[[177],[178],[179]]]]],[[[[[180],[181],[182]],[[183],[184],[185]],[[186],[187],[188]],[[189],[190],[191]]]],[[[[192],[193],[194]],[[195],[196],[197]],[[198],[199],[200]],[[201],[202],[203]]]],[[[[204],[205],[206]],[[207],[208],[209]],[[210],[211],[212]],[[213],[214],[215]]]]]],[[[[[[216],[217],[218]],[[219],[220],[221]],[[222],[223],[224]],[[225],[226],[227]]]],[[[[228],[229],[230]],[[231],[232],[233]],[[234],[235],[236]],[[237],[238],[239]]]],[[[[240],[241],[242]],[[243],[244],[245]],[[246],[247],[248]],[[249],[250],[251]]]]],[[[[[252],[253],[254]],[[255],[256],[257]],[[258],[259],[260]],[[261],[262],[263]]]],[[[[264],[265],[266]],[[267],[268],[269]],[[270],[271],[272]],[[273],[274],[275]]]],[[[[276],[277],[278]],[[279],[280],[281]],[[282],[283],[284]],[[285],[286],[287]]]]]]]]:
test__3 := [[[[[[[[-288],[-287],[-286]],[[-285],[-284],[-283]],[[-282],[-281],[-280]],[[-279],[-278],[-277]]]],[[[[-276],[-275],[-274]],[[-273],[-272],[-271]],[[-270],[-269],[-268]],[[-267],[-266],[-265]]]],[[[[-264],[-263],[-262]],[[-261],[-260],[-259]],[[-258],[-257],[-256]],[[-255],[-254],[-253]]]]],[[[[[-252],[-251],[-250]],[[-249],[-248],[-247]],[[-246],[-245],[-244]],[[-243],[-242],[-241]]]],[[[[-240],[-239],[-238]],[[-237],[-236],[-235]],[[-234],[-233],[-232]],[[-231],[-230],[-229]]]],[[[[-228],[-227],[-226]],[[-225],[-224],[-223]],[[-222],[-221],[-220]],[[-219],[-218],[-217]]]]]],[[[[[[-216],[-215],[-214]],[[-213],[-212],[-211]],[[-210],[-209],[-208]],[[-207],[-206],[-205]]]],[[[[-204],[-203],[-202]],[[-201],[-200],[-199]],[[-198],[-197],[-196]],[[-195],[-194],[-193]]]],[[[[-192],[-191],[-190]],[[-189],[-188],[-187]],[[-186],[-185],[-184]],[[-183],[-182],[-181]]]]],[[[[[-180],[-179],[-178]],[[-177],[-176],[-175]],[[-174],[-173],[-172]],[[-171],[-170],[-169]]]],[[[[-168],[-167],[-166]],[[-165],[-164],[-163]],[[-162],[-161],[-160]],[[-159],[-158],[-157]]]],[[[[-156],[-155],[-154]],[[-153],[-152],[-151]],[[-150],[-149],[-148]],[[-147],[-146],[-145]]]]]],[[[[[[-144],[-143],[-142]],[[-141],[-140],[-139]],[[-138],[-137],[-136]],[[-135],[-134],[-133]]]],[[[[-132],[-131],[-130]],[[-129],[-128],[-127]],[[-126],[-125],[-124]],[[-123],[-122],[-121]]]],[[[[-120],[-119],[-118]],[[-117],[-116],[-115]],[[-114],[-113],[-112]],[[-111],[-110],[-109]]]]],[[[[[-108],[-107],[-106]],[[-105],[-104],[-103]],[[-102],[-101],[-100]],[[-99],[-98],[-97]]]],[[[[-96],[-95],[-94]],[[-93],[-92],[-91]],[[-90],[-89],[-88]],[[-87],[-86],[-85]]]],[[[[-84],[-83],[-82]],[[-81],[-80],[-79]],[[-78],[-77],[-76]],[[-75],[-74],[-73]]]]]],[[[[[[-72],[-71],[-70]],[[-69],[-68],[-67]],[[-66],[-65],[-64]],[[-63],[-62],[-61]]]],[[[[-60],[-59],[-58]],[[-57],[-56],[-55]],[[-54],[-53],[-52]],[[-51],[-50],[-49]]]],[[[[-48],[-47],[-46]],[[-45],[-44],[-43]],[[-42],[-41],[-40]],[[-39],[-38],[-37]]]]],[[[[[-36],[-35],[-34]],[[-33],[-32],[-31]],[[-30],[-29],[-28]],[[-27],[-26],[-25]]]],[[[[-24],[-23],[-22]],[[-21],[-20],[-19]],[[-18],[-17],[-16]],[[-15],[-14],[-13]]]],[[[[-12],[-11],[-10]],[[-9],[-8],[-7]],[[-6],[-5],[-4]],[[-3],[-2,-0]]]]]]],[[[[[[-1],[[1],[2]],[[3],[4],[5]],[[6],[7],[8]],[[9],[10],[11]]]],[[[[12],[13],[14]],[[15],[16],[17]],[[18],[19],[20]],[[21],[22],[23]]]],[[[[24],[25],[26]],[[27],[28],[29]],[[30],[31],[32]],[[33],[34],[35]]]]],[[[[[36],[37],[38]],[[39],[40],[41]],[[42],[43],[44]],[[45],[46],[47]]]],[[[[48],[49],[50]],[[51],[52],[53]],[[54],[55],[56]],[[57],[58],[59]]]],[[[[60],[61],[62]],[[63],[64],[65]],[[66],[67],[68]],[[69],[70],[71]]]]]],[[[[[[72],[73],[74]],[[75],[76],[77]],[[78],[79],[80]],[[81],[82],[83]]]],[[[[84],[85],[86]],[[87],[88],[89]],[[90],[91],[92]],[[93],[94],[95]]]],[[[[96],[97],[98]],[[99],[100],[101]],[[102],[103],[104]],[[105],[106],[107]]]]],[[[[[108],[109],[110]],[[111],[112],[113]],[[114],[115],[116]],[[117],[118],[119]]]],[[[[120],[121],[122]],[[123],[124],[125]],[[126],[127],[128]],[[129],[130],[131]]]],[[[[132],[133],[134]],[[135],[136],[137]],[[138],[139],[140]],[[141],[142],[143]]]]]],[[[[[[144],[145],[146]],[[147],[148],[149]],[[150],[151],[152]],[[153],[154],[155]]]],[[[[156],[157],[158]],[[159],[160],[161]],[[162],[163],[164]],[[165],[166],[167]]]],[[[[168],[169],[170]],[[171],[172],[173]],[[174],[175],[176]],[[177],[178],[179]]]]],[[[[[180],[181],[182]],[[183],[184],[185]],[[186],[187],[188]],[[189],[190],[191]]]],[[[[192],[193],[194]],[[195],[196],[197]],[[198],[199],[200]],[[201],[202],[203]]]],[[[[204],[205],[206]],[[207],[208],[209]],[[210],[211],[212]],[[213],[214],[215]]]]]],[[[[[[216],[217],[218]],[[219],[220],[221]],[[222],[223],[224]],[[225],[226],[227]]]],[[[[228],[229],[230]],[[231],[232],[233]],[[234],[235],[236]],[[237],[238],[239]]]],[[[[240],[241],[242]],[[243],[244],[245]],[[246],[247],[248]],[[249],[250],[251]]]]],[[[[[252],[253],[254]],[[255],[256],[257]],[[258],[259],[260]],[[261],[262],[263]]]],[[[[264],[265],[266]],[[267],[268],[269]],[[270],[271],[272]],[[273],[274],[275]]]],[[[[276],[277],[278]],[[279],[280],[281]],[[282],[283],[284]],[[285],[286],[287]]]]]]]]:

Is there a generalized test procedure (e.g., ListTools:-IsRectangular) that effectively works for any nested list of an arbitrary nesting level?

which cod in grtensor for calculate a tt component...

Asked by: maryam sadeghi 25

September 09 2023

1 3

HI every one ! i want to know how can i calculate tt component and rr component in Einstein eq or Energy-Momentum eq.please give me a cod for drive component of any equation in maple

I am not able to solve these equation, can anyone ...

Asked by: Reshu Gupta 60

September 08 2023

0 4

restart;
Pr:=0.71: n:=-1:

eta0:=0.0699;

EQ1:=diff(H(x), x ) - x*diff(F(x), x ) ;

EQ2:=(1+x^2)*diff(F(x), x$2) + (3*x + x*F(x)-H(x))*diff(F(x), x) + F(x)^2 + G(x)^2 +2*P(x) + x*diff(P(x), x) ;

EQ3:=(1+x^2)*diff(G(x), x$2) + (3*x + x*F(x)-H(x))*diff(G(x), x) ;

EQ4:=(1+x^2)*diff(H(x), x$2) + (3*x + x*F(x)-H(x))*diff(H(x), x) + (1+F(x))*H(x)- diff(P(x), x);

EQ5:=(1+x^2)*diff(theta(x), x$2) + x*(1-2*n)*diff(theta(x), x) + n^2*theta(x) - Pr*( n*F(x)*theta(x) + ( H(x)-x*F(x) )*diff(theta(x), x) ) ;

EQ:={EQ1=0, EQ2=0,EQ3=0,EQ4=0 ,EQ5=0}:

IC:={ F(0)=0, G(0)=12, H(0)=0, theta(0)= 1, F(eta0)=0, G(eta0)=12, H(eta0)=0, theta(eta0)= 0, P(0)=0};

sol:= dsolve(EQ union IC,numeric,output=Array([0,0.0699]));

ques.mw

Can I convert a date time string into a form I can...

Asked by: FDS 160

September 08 2023

0 6

This is most likely a simple question for the power users of this forum, but I do not manage to find a solution. I have date in an Excel file. The first column consists of dates (mm/dd/yyyy) and the second of time (hh:mm). I can easily concatenate both in Maple using cat("9/7/2023", "10:22") but how can I convert the obtained string into a date+time that Maple understands?

Thank you in advance for your help.

How to solve a linear system with 7 variables and ...

Asked by: Newie 10

September 08 2023

2 7

I create a system of equations (with 9 linear equations and 7 variables).

I get 7 equations from the multiplication of a matrix M with a transposed vector of the 7 variables equals the transposed vector of the 7 variables. Other two simple equations are necessary because they are restrictions. Those two equations a re very simple and thave the 7 variable sin it.

To start I have been trying with fsolve but i haven't been able to solve it yet, as I also get the error: "Error, (in fsolve) number of equations, 9, does not match number of variables, 7"

Have you andy idea to solve this problem? Thanks in advance.

Problem getting a plot the way I want through plot...

Asked by: lemelinm 1490

September 07 2023

1 8

Below is the plot like I want it. The basic plot has been done with a simple plot command.

>plot(0, x = 0 .. 10, y = 0 .. 4, gridlines = true)

But the label of each axis was done manually. But I have tried to do it inside the plot command. A little help would be very appreciated.

So here is what I want the plot to look like:

Thank you in advance for the help.

Mario

Plotting pseudospectra...

Asked by: rzarouf 25

September 07 2023

2 9

Hi everyone,

Do you know if there are some known codes for plotting pseudospectra of squared (and finite) matrices with given spectrum ?
Thanks in advance

Best,

Rachid

What will be the range of p and q to get the plot ...

Asked by: MANUTTM 30

September 07 2023

0 6

What will be the range of p and q to get the plot and to get the optimum solution?
If possible get a solution for particular value of p and q.
file attached: q1.mw

How to find the value of constants?...

Asked by: Rana47 15

September 07 2023

0 3

Hi all, any one help me to find the values of constants by using given condition and then how to varify that the goiven condition varify the expression. I have found manually but want to varify through maple.

help.mw

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