MaplePrimes Questions

 

I have installed in my UBUNTU 16.04 system matlab 2018a already, I have recently acquired maple 2017.3 (through my university).

Now while trying to install maple in my computer I am at the matlab configuration option, I picked the directory where the matlab installation is situated at, and I get the following error: The directory /home/alon/MATLAB/R2018a/bin/matlab is not writable by the current user

I searched google for this occurrence of error, and found the following suggestion: https://askubuntu.com/questions/265381/how-to-make-a-directory-permanently-writable

the first answer suggests to write in the terminal the following line: sudo chmod 775 /home/alon/MATLAB/R2018a/bin/matlab

which I did but I still get after executing this line in the terminal the above error; what else can I do to fix this problem?

Thanks.

Hi everyone.

I am trying to build a package in Maple out of a bunch of procedures that I have. To create the procedures, I write them on a Vim editor, than copy and paste into the Maple worksheet to test. In this way, it works (I end the procedure with ; and then I see all the text in blue and I afterwords test it).

I then gathered these procedures to a module, option package, and I do the same: edit on Vim, copy paste it to Maple worksheet and press enter to see a blue message "module() ... end module" in blue, and then I start playing.

However, I decided to add some more procedures to the module that was working. I have a new procedure that works (meaning when I copy to the worksheet it gives the blue text and I can call normally), but when I copy the contents of this new procedure inside the package, with all the others, and I copy everything to the worksheet, the package now fails to work. It gives a message "Error," in pink, no more text, and that is it. Does this sort of error sound familiar to anyone? Thanks in Advance,

Marcelo

I wanted to make a 3d plot with lines linking points, but I am struggling with it
(I couldn't find anything in the plot3d documentation, so it might not be supported, which would be odd as its such a normal thing to want to do)

I have tried with no success:

plot3d([1, 2, 3], [4, 5, 6]);
plot3d(Matrix(2, 3, {(1, 1) = 1, (1, 2) = 2, (1, 3) = 3, (2, 1) = 4, (2, 2) = 5, (2, 3) = 6}))

Any thoughts?

i have two functions , first naive function has error after used.
 
if run FromMatlab, does it mean that do not need to copy the result and run again because it had already run?
as i do not understand the output code after translated.
 
there is syntax error when translate second function
 
with(Matlab):
FromMatlab("function X = sylv_naive(A,B,Q)
% X=SYLV_NAIVE(A,B,Q) solves the Sylvester equation AX + XB = Q
%    A, B, Q: matrix coefficients
%    X : solution of AX + XB = Q
[m,n] = size(Q);
H = kron(eye(n), A) + kron(B.', eye(m));
Qvec = reshape(Q,m*n,1);
Xvec = H\Qvec;
X = reshape(Xvec,m,n);
");
sylv_naive(Jesus7,Jesus7,Matrix([[0,0],[0,0]]));
sylv_naive(Jesus7,Jesus7,Matrix([[0],[0]]));
Error, (in ArrayTools:-Reshape) the desired output contains a different number of elements than the input
 
 
 
with(Matlab):
FromMatlab("function X = sylvester(A,B,Q)
% X=SYLVESTER(A,B,Q) solves the Sylvester equation AX + XB = Q
% by using the Bartels and Stewart algorithm based on the complex
% Schur decomposition
%    A, B, Q: matrix coefficients
%    X : solution of AX + XB = Q
[m,n] = size(Q);
[U,A1] = schur(A,'complex');
[V,B1] = schur(B.','complex');
Q1 = U'*Q*conj(V);
X = zeros(m,n);
X(:,n) = (A1 + B1(n,n)*eye(m))\Q1(:,n);
for i = n-1:-1:1
    v = Q1(:,i) - X(:,i+1:n)*B1(i,i+1:n).';
    X(:,i) = (A1 + B1(i,i)*eye(m))\v;
end
X = U*X*V.';");

Error, (in Matlab:-FromMatlab) on line 15, syntax error
    X(:,i) = (A1 + B1(i,i)*eye(m))
 
 

I wrote this simple set of instructions  (Maple 2015 and Maple 2016)

restart:
p := x -> sum('a__||k' * x^k, k=0..5):
p(x);    # returns a0+ a1x +  ... + a5x5

p(1);   # returns a0+ ... + a5

p(0);   # returns 0 ...  not a0


Probably so huge a mistake that I can't see it !?!?!?

Could you please help me to fit it ?

TIA

LettR_curvefitting.mws

Am in the process of trying to addsome animation to a 2D letter R, namely to make the 'stalk' move.  I lost the output and managed to retrieve it by adding  verboseproc=0, and printlevel:=5.  However printlevel:=5 gives an excessive amount of output and anything less than 5 doesn't give enough output.  The code is messy asI've been experimenting with general curve fitting.

   Any help gratefully received. 

I have a problem with writing this equation in maple.

the equation is: 

I want to write this equation in maple, so I write it in this way:

for k from 1 to 7 do tau[k] := add*(d(k, j)*(diff(theta[j](t), t, t)), j = 1 .. 7)+add(add(c[i, j, k]*(diff(theta[i](t), t))*(diff(theta[j](t), t)), j = 1 .. 7), i = 1 .. 7)+phi[k] end do:

but I see this error: Error, index out of bounds 

I appriciate if you help me find the problem.

Why is assume(...) do_something();  gives an error when I run the code one more time, but do_something() assuming ...; do not give an error when everything else is the same?

Is there semantic difference between the two forms? I thought they should work the same way. Here is an example

#in separate cell
restart;

#in separate cell
interface(showassumed=0):
pde := diff(u(x, t), t)=k*diff(u(x, t), x$2):
ic:=u(x,0)=0: bc:=u(0,t)=t:
assume(x>0);assume(t>0);assume(k>0):
sol:= pdsolve({pde,ic,bc},u(x,t)):

#in separate cell. Now this gives error
interface(showassumed=0):
pde := diff(u(x, t), t)=k*diff(u(x, t), x$2):
ic:=u(x,0)=0: bc:=u(0,t)=t:
assume(x>0);assume(t>0);assume(k>0):
sol:= pdsolve({pde,ic,bc},u(x,t)):
#error message now

Here is screen shot

Now will do the same, but use assuming. Now there is no error

#in one cell
restart;

#in one cell
interface(showassumed=0):
pde := diff(u(x, t), t)=k*diff(u(x, t), x$2):
ic:=u(x,0)=0: bc:=u(0,t)=t:
sol:= pdsolve({pde,ic,bc},u(x,t)) assuming x>0,t>0,k>0:

#in one cell, no error
interface(showassumed=0):
pde := diff(u(x, t), t)=k*diff(u(x, t), x$2):
ic:=u(x,0)=0: bc:=u(0,t)=t:
sol:= pdsolve({pde,ic,bc},u(x,t)) assuming x>0,t>0,k>0:

Here is screen shot

Why does one give an error, but the second one does not?

I thought they work the same way. Which method is recommended to use?

assume(...); do_something(); 

or 

do_something() assuming ...;

Maple 2018 on windows.

equ.pdf The equation is in the following form:

 

Hello,

     I'm attempting to use unevaluation quotes on a keyword argument within a procedure. For instance, if I have two procedures with the same keyword arguments, I need to unevaluate one to call the other:

foo1 := proc( {param:={}}, $)
  foo2('param'=param):
end proc:


foo2 := proc( {param:={}}, $)
end proc:

foo1('param'=1);

The above code throws the error,

Error, (in foo1) invalid input: too many and/or wrong type of arguments passed to foo2; first unused argument is 1 = 1

which I take to mean that 'param' in foo1 isn't being unevaluated in the call to foo2. What is the correct way to accomplish this?

Thanks!

Is it possible to get the following integral involving vectors done in Maple 2018, but handle the singularity when p1=p3?

Note that the output of p3 and p1 are slightly different, probably because the earlier version of the worksheet was in Maple 2017? 

(Note: Earlier version - was due to help received from Dr. Edgardo Cheb-Terrab, using Maple 2017). 

 
with(Physics[Vectors]);
r_ := _i*x+_j*y+_k*z;
                    r_ := _i x + _j y + _k z
p__1_ := _i*`p__1x `+_j*`p__1y `+_k*`p__1z `;
           p__1_ := _i p__1x  + _j p__1y  + _k p__1z 
p__3_ := _i*`p__3x `+_j*`p__3y `+_k*`p__3z `;
           p__3_ := _i p__3x  + _j p__3y  + _k p__3z 
Expression to integrate wrt p3
'exp(i*(p__1_ . r_))/((p__3_ - p__1_)^2)'
             exp(I Physics:-Vectors:-.(p__1_, r_))
             -------------------------------------
                                                2 
              Physics:-Vectors:-+(p__3_, -p__1_)  
Delaying the evaluation above, if evaluation is allowed, the integrand is
exp(I*(p__1_ . r_))/(p__3_-p__1_)^2;
(exp(I (p__1x  x + p__1y  y + p__1z  z)))/((_i (-p__1x  + p__3x )

   + _j (-p__1y  + p__3y ) + _k (-p__1z  + p__3z ))^2)
T i is the imaginary unit
interface(imaginaryunit = I);
                               I
Because (4), has the value of i before being the imaginary unit, input the integrand again
'exp(i*(p__1_ . r_))/((p__3_ - p__1_)^2)'
             exp(I Physics:-Vectors:-.(p__1_, r_))
             -------------------------------------
                                                2 
              Physics:-Vectors:-+(p__3_, -p__1_)  


Now on the integration
Int(exp(I*(p__1_ . r_))/(p__3_-p__1_)^2, [`p__3x ` = -infinity .. infinity, `p__3y ` = -infinity .. infinity, `p__3y ` = -infinity .. infinity]);
  /infinity   /infinity   /infinity                            
 |           |           |                                     
 |           |           |          (exp(I (p__1x  x + p__1y  y
 |           |           |                                     
/-infinity  /-infinity  / -infinity                            

   + p__1z  z)))/((_i (-p__1x  + p__3x ) + _j (-p__1y  + p__3y )

   + _k (-p__1z  + p__3z ))^2) dp__3x  dp__3y  dp__3y 
value(Int(exp(I*(`p__1x `*x+`p__1y `*y+`p__1z `*z))/(_i*(-`p__1x `+`p__3x `)+_j*(-`p__1y `+`p__3y `)+_k*(-`p__1z `+`p__3z `))^2, [`p__3x ` = -infinity .. infinity, `p__3y ` = -infinity .. infinity, `p__3y ` = -infinity .. infinity]));
                                         /         /[          
 exp(I (p__1x  x + p__1y  y + p__1z  z)) |PIECEWISE|[infinity, 
                                         \         \[          

   Im(_i p__1x  + _j p__1y  + _k p__1z  - _k p__3z )    ]  
   ------------------------------------------------- = 0], 
                          _i                            ]  

                 \\         
   [0, otherwise]|| infinity
                 //         
In the above, there is the product of three Dirac delta functions, that can be represented as a single 3D Dirac delta
combine(exp(I*(`p__1x `*x+`p__1y `*y+`p__1z `*z))*piecewise(Im(_i*`p__1x `+_j*`p__1y `+_k*`p__1z `-_k*`p__3z `)/_i = 0, infinity, 0)*infinity);
                                         /         /[          
 exp(I (p__1x  x + p__1y  y + p__1z  z)) |PIECEWISE|[infinity, 
                                         \         \[          

   Im(_i p__1x  + _j p__1y  + _k p__1z  - _k p__3z )    ]  
   ------------------------------------------------- = 0], 
                          _i                            ]  

                 \\         
   [0, otherwise]|| infinity
                 //         

 

Hello. Tell me please how to fix it and build a graph? Thank you in advance.

p := PolyhedralSets([-x >= 0, -y >= 0, -z >= 0, -(1/2)*x >= 0, (-x-y)*(1/2) >= 0, (-x-z)*(1/2) >= 0], {y = -20}, [x, y, z]);
plot(p);
Error, (in plot) cannot determine plotting variable
 

Hello,

I wonder why trigonometric functions in the Trig Identities context menu in this new release are now suddenly printed italic like cos(x). It's not only inconsistent with the display of functions everywhere else within Maple, also every LaTeX user with very little knowledge of mathematical typesetting rules will frown at the sight of this.

I know it's not a big thing but Maple always stresses to produce pretty-print textbook style output. Powers of trigonometric functions like tan(theta)^2 as shown in the attached screenshot would however be printed like tan^2(theta) in textbooks just as when written by hand.

There are quite some examples where Maple uses significantly strange typesetting like total derivatives dx dy dz in the Physics package that are typeset as partial derivatives. I wonder why Maple introduced a partial-d but not also a total-d operator - doesn't that kind of hurt the eye even if the functionality is beyond critique? That's actually the only case that comes to my mind right now where even Mathematica's typesetting resembles mathematics in textbooks more closely and displays mathematical content more pleasantly than Maple does.

Good day. Please can someone kindly help to reduce the result of this code. Thank you and kind regards

restart:
s:=(sum(a[j]*x^j,j=0..3)+sum(a[j]*exp(-(j-3)*x),j=4..7)):
F:=diff(s,x):
p1:=simplify(eval(s,x=q))=y[n]:
p2:=simplify(eval(F,x=q))=f[n]:
p3:=simplify(eval(F,x=q+h/3))=f[n+1/3]:
p4:=simplify(eval(F,x=q+h))=f[n+1]:
p5:=simplify(eval(F,x=q+5*h/3))=f[n+5/3]:
p6:=simplify(eval(F,x=q+2*h))=f[n+2]:
p7:=simplify(eval(F,x=q+7*h/3))=f[n+7/3]:
p8:=simplify(eval(F,x=q+3*h))=f[n+3]:


vars:= seq(a[i],i=0..7):
Cc:=eval(<vars>, solve({p||(1..8)}, {vars})):
for i from 1 to 8 do
	a[i-1]:=Cc[i]:
end do:
Cf:=s:
L:=collect(simplify(simplify(expand(eval(Cf,x=q+3*h)),size)), [y[n],f[n],f[n+1/3],f[n+1],f[n+5/3],f[n+2],f[n+7/3],f[n+3]], factor):
length(L);
H := ee -> collect(numer(ee),[exp],h->simplify(simplify(h),size))/collect(denom(ee),[exp],h->simplify(simplify(h),size)):
M:=y[n+3]=(H@expand)(L);
length(M);

 

CurveFitting.mws

Splines and BSplines etc for curve fitting.

The attached short program uses with(CurveFitting) and BS:=BSpline(2,x);  outputs four expressions, the third being 

2-x, x<2.  I'd like to be able to access this, and plot it. but plots[display](BS[3], x=1..2); comes up with an error message.

Thanks in advance for any help. 

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