Unanswered Questions

This page lists MaplePrimes questions that have not yet received an answer

f(x) := piecewise(0 < x, x^(3/2)*sin(1/x), x = 0, 0, undefined);
plot(f(x));

gives me the following error:

Error, (in plot) incorrect first argument piecewise(0 < x, (HFloat(2.739493386336394e-116)+HFloat(2.739493386336394e-116)*I)*x^(3/2), x = 0, 0, undefined)

I just want to see the function plot. With Wolfram Alpha this is no deal at all!
 

Maple doesn't completely check the condition on the number of trials "n" for Binomial and NegativeBinomial distributions (package Statistics).
The attribute "Conditions" explicitely says that n must be a strictly positive integer but no strictly positive real valuereturna an error (ok, it would be stupid to set n to a non integer value !!!).

I think it is a default that ought to be corrected in future releases (this default still exists in Maple 2018)

 

restart

kernelopts(version)

`Maple 2015.2, APPLE UNIVERSAL OSX, Dec 20 2015, Build ID 1097895`

(1)

with(Statistics):


BINOMIAL DISTRIBUTION

X := RandomVariable(Binomial(n, p)):
L := [attributes(X)][3]:
A := exports(L)

Conditions, ParentName, Parameters, CDF, CharacteristicFunction, Kurtosis, Mean, Median, Mode, MGF, ProbabilityFunction, Skewness, Support, Variance, VariationCoefficient, CDFNumeric, QuantileNumeric, RandomSample, RandomSampleSetup, RandomVariate

(2)

L:-Conditions

[0 <= p, p <= 1, n::posint]

(3)

# Maple should return an error for N is not of type posint
#
# It seems that Sample uses floor(N)

N := 10.49; type(N::posint);
P := 1/2:
X := RandomVariable(Binomial(N, P)):
Mean(X), N*P;
ProbabilityFunction(X, k);
S := Sample(X, 10^6):
Mean(S);


# A non consistent result (only non negative values of k should be accepted)

eval(ProbabilityFunction(X, k), k=evalf(Pi));

N := 10.49

 

false

 

5.245000000, 5.245000000

 

piecewise(k < 0, 0, binomial(10.49, k)*(1/2)^k*(1/2)^(10.49-k))

 

HFloat(4.998903)

 

.1096019539

(4)


NEGATIVE BINOMIAL DISTRIBUTION

X := RandomVariable(NegativeBinomial(n, p)):
L := [attributes(X)][3]:
A := exports(L):
L:-Conditions

[0 < n, 0 < p, p <= 1]

(5)

N := 10.49:
P := 1/2:
X := RandomVariable(NegativeBinomial(N, P)):

Mean(X)


 

Download BinomialLaw.mw

 

Yeah, i have tried evalf[10](sqrt(25)).
How can i get a simple number as answer? I'm loving the software but i just wished i could type in:
int(sin(x), x = 0 .. pi)
and get 2 instead of (2.739493386*10^(-116) + (2.739493386*10^(-116))*I)*pi.
Also, when i type evalf[50](pi), i wish to get all the 50 digits, but i just get \pi :/.
Please help me.

I want to solve an ODE system numerically, but maple show not converge for iteration, can you give a solution
with(VectorCalculus);
with(linalg);


pi := 4; eta := 6; mh := .1; mv := .3; bh := .15; Nh := 400; Nv := 200; bv := .25; b := .8; d := .1; p := .5; B := 10; A := 1; alpha := .25; beta := .7; K := 400; r := .5; c := .9; q := .8; Sh0 := 225; Sv0 := 100; Ih0 := 175; Iv0 := 600; P0 := 50; T := 35; B := 10;
                  


eq1 := diff(L1(t), t) = -L1(t)*(-bh*b*Iv(t)/Nh-mh)-L2(t)*bh*b*Iv(t)/Nh; eq2 := diff(L2(t), t) = -L2(t)*(-mh-d)+L3(t)*bv*b*Sv(t)/Nv-L4(t)*bv*b*Sv(t)/Nv; eq3 := diff(L3(t), t) = -(L4(t)*Iv(t)+L3(t)*Sv(t))*L3(t)/(2*B^2)-L3(t)*(-bv*b*Ih(t)/Nv-mv-L3(t)*Sv(t)/(2*B^2)-(L4(t)*Iv(t)+L3(t)*Sv(t))/(2*B^2)-P(t)*alpha)-L4(t)*(bv*b*Ih(t)/Nv-L3(t)*Iv(t)/(2*B^2))-L5(t)*P(t)*alpha; eq4 := diff(L4(t), t) = -A-(L4(t)*Iv(t)+L3(t)*Sv(t))*L4(t)/(2*B^2)+L1(t)*bh*b*Sh(t)/Nh-L2(t)*bh*b*Sh(t)/Nh+L3(t)*L4(t)*Sv(t)/(2*B^2)-L4(t)*(-mv-L4(t)*Iv(t)/(2*B^2)-(L4(t)*Iv(t)+L3(t)*Sv(t))/(2*B^2)-P(t)*alpha)-L5(t)*P(t)*alpha; eq5 := diff(L5(t), t) = L3(t)*Sv(t)*alpha+L4(t)*Iv(t)*alpha-L5(t)*(r*(1-P(t)/Nv)-P(t)*r/Nv+alpha*(Sv(t)+Iv(t))-q*c); eq6 := diff(Sh(t), t) = pi-bh*b*Sh(t)*Iv(t)/Nh-mh*Sh(t); eq7 := diff(Ih(t), t) = bh*b*Sh(t)*Iv(t)/Nh-mh*Ih(t)-d*Ih(t); eq8 := diff(Sv(t), t) = eta-bv*b*Sv(t)*Ih(t)/Nv-mv*Sv(t)-P(t)*Sv(t)*alpha-L3(t)*Sv(t)^2/(2*B^2)-L4(t)*Sv(t)*Iv(t)/(2*B^2); eq9 := diff(Iv(t), t) = -L3(t)*Sv(t)*Iv(t)/(2*B^2)+bv*b*Sv(t)*Ih(t)/Nv-mv*Iv(t)-P(t)*Iv(t)*alpha-L4(t)*Iv(t)^2/(2*B^2); eq10 := diff(P(t), t) = P(t)*r*(1-P(t)/Nh)+P(t)*alpha*(Sv(t)+Iv(t))-q*P(t)*c

fcns := {Ih(t), Iv(t), L1(t), L2(t), L3(t), L4(t), L5(t), P(t), Sh(t), Sv(t)}; a := dsolve({eq1, eq10, eq2, eq3, eq4, eq5, eq6, eq7, eq8, eq9, Ih(0) = Ih0, Iv(0) = Iv0, L1(T) = 0, L2(T) = 0, L3(T) = 0, L4(T) = 0, L5(T) = 0, P(0) = P0, Sh(0) = Sh0, Sv(0) = Sv0}, fcns, type = numeric);
fcns := {Ih(t), Iv(t), L1(t), L2(t), L3(t), L4(t), L5(t), P(t), 

  Sh(t), Sv(t)}
Error, (in dsolve/numeric/bvp) initial Newton iteration is not converging

 

Dear Maple user  help required to  evaluate the values of u and v from  coupled difference scheme  and plot the 2D multiple curves by changing the values of M  and R .  By seeing mapleprime post i have written sample codes  

 

restart; Digits := 5; with(plots); with(LinearAlgebra);
#Parameter values:
a:=0:b:=2:N:=9:
h:=(b-a)/(N+1): phi:=0.5:
K:=10^(-6):mu:=1.67:
alpha:=K/(phi*mu):lambda:=alpha*k/h^2:

#Initial conditions
for i from 0 while i <= N do u[i, 0] := h*i+1 end do;

#Initial conditions
for i from 0 while i <= N do v[i, 0] := h*i+1 end do;


#Boundary conditions
for j from 0 while j <= N+1 do u[0, j] := .1; u[N+1, j] := .5 end do;

#Boundary conditions
for j from 0 while j <= N+1 do v[0, j] := .2; v[N+1, j] := R end do;

#Discritization scheme
printlevel := 2; for i while i <= N do for j from 0 while j <= N do eq1[i, j] := lambda*u[i-1, j]+(M.(2-2*lambda))*u[i, j]+lambda*u[i+1, j] = -lambda*u[i-1, j+1]+(2+2*lambda)*v[i, j+1]-(M.lambda)*u[i+1, j+1] end do end do;

#Discritization scheme
printlevel := 2; for i while i <= N do for j from 0 while j <= N do eq2[i, j] := lambda*v[i-1, j]+3*lambda*v[i, j]+(M.lambda)*v[i+1, j] = -lambda*u[i-1, j+1]+(M.(7-2*lambda))*u[i, j+1]-lambda*v[i+1, j+1] end do end do;
# how to solve the two equations (1 and 2) in terms to calculate the values of u and v and plot the graphs in 2 dimension while #changing the values of M=0,5,10 (variable), R=0,0.5,0.7
# I am unable to write the codes  further


###############################################################
restart:
#sys := ([seq])(seq(eq[i, j], j = 0 .. N), i = 1 .. N):
nops(sys);
vars:=indets(sys) minus {k}:
nn := Matrix(N+1, N+1,(i, j)-> u[i-1, j-1]):
##
p:=proc(kk) local u_res,A;
  u_res:=solve(eval(sys,k=kk),vars);
  A:=eval(nn,u_res);
  plots:-matrixplot(A)
end proc;
## Testing p for k=0.001:
p(0.001);
## Animating the plot for k=0.0001..0.001:
plots:-animate(p,[k],k=0.0001..0.001);
#################################################################
 

 

Does maple provide any platform for running calculation something like cloud facility

Dear Maple users

Some students have come to us to report, that something doesn't seem to work properly in Maple 2019.1 in Document Mode. And they seem to be right: writing an passive math formula by using Shift+F5 (the formula is gray, not blue), then using F5 to get out of that Math field and back into Text Mode. Using the Enter key to go to the next line: It doesn't work! The cursor stays in the same line. This behavior is new in Maple 2019. It worked properly in Maple 2018 and earlier. I assume it is not the intention? 

I know it can easily be dealt with by making a new Paragraph by using the shortcut Ctrl+Shift+J. I call the assumed bug 'severe' though, because it will severely delay the workflow for many students. They are used to deliver a document mixed with formulas (active or passive) and text. 

NB! I have tested it on several computers (Mac and Windows), and it doesn't work on any of them.

Regards,

Erik V.

i have a question about sets. how can i keep set members in order of addition not the defualt maple ordering.
in maple help, i saw the command setsort=0..8 but i do not know how to use it.
consider exmaple below:


 

restart

L:={}:

for j in [3,5,6,1] do
birth:=j:
L:=`union`(L ,{j});
od;

3

 

{3}

 

5

 

{3, 5}

 

6

 

{3, 5, 6}

 

1

 

{1, 3, 5, 6}

(1)

 


how can i keep L as order of addition? L={3,5,6,1}. thanks in advance

Download setoder.mw

I've recently changed to maple 2019, from the 2016 version as my license for that product had expired. 
However I find it really frustrating that often upon evaluating an expression I can't convert the units. 

For instance I had a calculation that evaluated to: 

2.114163508*10^7 [kg/s^2]
 

When I try to directly replace the units within maple to instead be [J/m^2] I recieve the following error message: 


"Error, (in  Units:-TestDimensions) 'op(3, i) does not  evaluate to module" 

There is no explanation for this error when I try to look it up. However if I once again manually write the answer: 
2.114163508*10^7 [kg/s^2] and use the replace units function. 
No problem. 
I find this quite annoying and frustrating and I hope you can help.
 

Best regards 

Anders Alexander Wagenblast 

This is may be a philosophical question. But sometimes Maple suprises me when telling it to "simplify" expression. As in this example.

expr:=1/(y^3+1)^(2/3);

1/(y^3+1)^(2/3)

int(expr,y)

y*hypergeom([1/3, 2/3], [4/3], -y^3)

simplify(%)

(2/9)*y*Pi*3^(1/2)*LegendreP(-1/3, -1/3, (-y^3+1)/(y^3+1))/((-y^3)^(1/6)*(y^3+1)^(1/3)*GAMMA(2/3))

 


For me, the original result is "simpler". (Not only smaller leaf count, but it has one special function, vs. two: Legendre and Gamma). But may be Maple considers hypergeom always more "complex" than any other?

That is why I use simplify(expr,size) because I am scared of simplify without any option, as I have little idea how it decides which is simpler.

Any thoughts from the experts on how Maple decided to simplify something when no option is used? What kinds of rules it uses to decide how to transform the expression?

Maple 2019.1

 

Download simplify.mw

The video component is going to save me alot of hassle in that I was previously building external java applications for audio visual analysis purposes, with the downside of course being that I didnt have maple code at my disposal. 

I read in the manual for the video component that I can provide a HTTP address for which a video is located, which would mean i could probably stream an IP camera, but I can I use the localhost IP address with some sort of extension that directs to the I/O of a webcamera connected to my local machine?

Hi all, how to write description, suggestions for method (procedure) like image below. I tried searching for a solution but can't. Thank you very much

Is there extendable combinatorics experiment architect system design

such as new method can combine or use with old method and find relationship between them , these kind of big data system design in combinatorics experiment design?

How can I fix the error of ChangeOfVariables: Error, (in Student:-MultivariateCalculus:-ChangeOfVariables) unable to solve the change-of-variables equations for the original variables ?

Thanks!

Dear Maple users

 

I am just curious about how far Maplesoft is updating the Mac version of Maple to 64 bit (Catalina). This version of the Mac OS will hit the shelves in late September this year. As I have been told, no program built on 32 bit will be able to run on this new version of Mac OS. I am pretty sure there will be a lot of software troubles for students upgrading to this version. We can recommend the students not to upgrade immediately, but it would be interesting to hear how far Maplesoft is creating a 64 bit Maple-installer for Mac?

 

Regards,

Erik V.

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