The simple test procedure P constructs a large matrix.
Measuring the real time twice  (t1 and t2), t2 was by about 25% larger!
Now, if we remove the comment  before "Start",  t1 increases by 25% and t2 ~ t1.
So, the timing depends on whether some output is already on screen (standard interface).
Can you explain this?

restart;
P := proc(n,A)
  local i, j;
  for i from 1 to n do  for j from 1 to n do
    A[i,j]:=sin(arcsin(1/i-1/j+1/n))-1/i+1/j-1/n+i+j
  od od;
  NULL  #A;
end proc:

# "Start";
n := 300:
s := time[real]():
A:=Matrix(n,datatype=float[8]):
P(n,A):
t1:=time[real]()-s;

s := time[real]():
A:=Matrix(n,datatype=float[8]):
P(n,A):
t2:=time[real]()-s;
t2/t1;  # 1.24   WHY?

(For one of my programs, I found t2/t1 = 1.7)

Hi, 

Why does the use of  global  at the top level of a worksheet is no longer accepted in the most recent versions of Maple (it still was in Maple 2015), but only within procedures?

TIA

Hello,

How I can Plot this structure using define new coordinate such as cylinderical om\ne or addcoords?

plot.mw

eq:= x^2-y^2*z-y*z^2;

plot3d(eq,x=0..1,y=0..1);

memory used=177.9MB, alloc=44.3MB, time=2.29
Picked up JAVA_TOOL_OPTIONS:
Initializing Java runtime environment.
munmap_chunk(): invalid pointer
Error, (in Maplets:-Display) computation interrupted

Suppose I have the equation C := y^2*z + yz^2 = x^2, then I want to test for which triples (x,y,z) with x,y,z in {0,1} the equation is satisfied? Is there a quick way of doing this in Maple?

Hello,

I'm having some difficulty solving a set of equations. For example

dn/dt = Const*(phi - n)

ds/dt= Const*(phi-n)

s = d2 phi/dx2 + d2 phi/dy2

How do you solve a system like this? It is 2 equations with 2 unknowns, but it is the s variable that is evolved, i.e. ds/dt, instead of phi.

Anyone know of some code that could do this? (periodic boundary conditions)

Better yet, how do you formulate this as a regular ODE for n and phi?

 

I stumpled upon an exercise involving calculating double points for the spacecurve for a vector function defined in the plane. It reduces to solving two equations with two variables. The command solve is usually the way to find solutions, but since the equation contain a trigonometric function, Maple gives the solutions parametrized by aritrary constants _Z and _B. It is however cumbersome to 'decipher' the possible solutions as I do in the attached Maple file.  

I wonder if Maple have a way to deliver the solutions numerically in the interval from -4 to 4? If it had been a single equation this would have been possible, I know. 

NB! I know I can use the symmetri in the current example, but I am interested in a general technique to solve these kind of equations. 

Download Solving_system_of_equations_including_trigonometric_functions.mw

Regards,

Erik

Dear Users!

Hope everyone fine here. I have following three quires that need to be fix.

1. I want to collocate Vector IntXYZ1 and IntXYZ2 present in file Q1 in such a way that the first M1M2 + 2(M3-1)M2 + 2(M3-1)(M1-2) rows are zero and other rows are collocated at x=(i-1)/(M1-1), y=(j-1)/(M2-1), t=(k-1)/(M3-1) for i = 2,3,…,M1-1, j = 2,3,…,M2-1, k = 2,3,…,M3 as given as XX (of order 27 by 27 with first 25 rows are zero) for M1=M2=M3=3

2. Next, in file Q2 we have a Vector b with some entries which are actually the values of chi[1, 1, 1], chi[1, 1, 2],...,chi[2, 2, 2] in such a following way

(Vector(8, {(1) = chi[1, 1, 1], (2) = chi[1, 1, 2], (3) = chi[1, 2, 1], (4) = chi[1, 2, 2], (5) = chi[2, 1, 1], (6) = chi[2, 1, 2], (7) = chi[2, 2, 1], (8) = chi[2, 2, 2]})) = (Matrix(8, 1, {(1, 1) = 0, (2, 1) = 0, (3, 1) = 0, (4, 1) = 0, (5, 1) = 1.000000000, (6, 1) = 1.000000000, (7, 1) = 1.000000000, (8, 1) = .3678794412}))

Matrix B given in file Q2 have entires which are the linear cobiniation of chi[1, 1, 1], chi[1, 1, 2],...,chi[2, 2, 2]. I want to evaluate matrix B at the values of chi[1, 1, 1], chi[1, 1, 2],...,chi[2, 2, 2] which are obtained in vector b.

3. I want to recall a vector B in file Q3 at highlighted portion and B matrix is present in Q4. Which is the command to recall or export a matrix which contain in some other file like in file Q4.

I shall be very grateful for your support.

Q1.mw, Q2.mw, Q3.mw, Q4.mw

 Let d an integer ">=5 " and 
                    "lambda  in ]-(1)/(2),-(1)/(d+1)[. "
Put
> gamma[s+1,d]=((s+1)[d]((d+1)lambda+s))/(2^(d+1)(lambda+s)[d+1]).;
We need to show that
> gamma[s+1,d]>=-(1)/(2^(s+1)),;
for 
> s=1,...,[(d+1)/(2)].;
                                   
 a[k] designates the pochhammer symbol.

Thanks a lot 

Would anybody tell me that what does it mean

Warning, A new binding for the name `pdetest` has been created. The global instance of this name is still accessible using the :- prefix, :-`pdetest`.  See ?protect for details. pdetest

Does it mean that the solution satisfies the main equation? because doing manual calculations doesn't satisfy.

Here is my file test_3.mw

I am currently struggling with a piecewise functions. Seeing as this function is defined over a large number of breakpoints, it would seem that Maple is unable to execute a certain integration (over a particular interval). Since the first derivatives match up at all breakpoints and the piecewise function looks perfectly smooth to my eyes, I figured that I might obtain a sensible result approximating the function by means of a polynomial and integrating based on the resulting approximation. When I try to use minimax from numapprox, however, I just receive an error message to the effect that:

Error, (in evalf/int/CreateProc) function does not evaluate to numeric

I'd very much appreciate it if anyone had any pointers on how I might find a reasonably precise (not necessarily polynomial) approximation for a seemingly smooth piecewise function with a large number of breakpoints.

Many thanks.

Edit: Please find attached my worksheet: worksheet.mw. My goal is to approximate the function Z over the interval 5/3 to 5 by something that is not defined in a piecewise manner.

Dear all

I have a matrix defined using loop 

How, can I print the value of the  matrix

Print_vaue_G.mw

thank you

Dear all

I have a table with entries obtained using maple code, how can I copy this table to powepoint as image 

many thanks

How do we replace D^i by diff(y(x),x$i) in did:=D^14+23*D^13+144*D^12
in Maple 13?

Thank you!

mapleatha

I have the expression:

This works (Ans. 144):

coeff(144*D^10,D,op(2,op(2,144*D^10)));

This works (Ans. 144):

coeff(op(3,did),D,op(2,op(2,op(3,did))));

Why doesn't this work?

eval(coeff(op(i,did),D,op(2,op(2,op(i,did)))),i=3);

Why doesn't this work?

subs(i=3,coeff(op(i,did),D,op(2,op(2,op(i,did)))));

I need those "generic" substituions for certain loops that I am making.

Thank you!

mapleatha