Hi everybody,

I have differential equation of the form eq := diff(x(t), t) = x(t) + 1  and I want to find the name of the dependent variable (more generally this issue concerns a differential system in N dependent variables).

How should I use “indets” in order to obtain {t, x(t)} ?

(indets(eq, name) returns {t}, while indets(eq, function) returns {t, x(t), d/dt x(t)}.

Thanks in advance

Perhaps I am being stupid, but I have a problem with functional operators, more specifically with looping through a collection of them. Consider the following code (just a study case):

nonIdMaps := []:
for f in [x -> x,x -> 2*x,x -> 3*x] do
   f,f(y);
   if f(y) <> y then nonIdMaps := [nonIdMaps[],f] end if
end do;
nonIdMaps,map(f -> f(y),nonIdMaps);

There are two things I do not understand about this output: 1.) Why the f's rather than the specific maps as given in the list? 2.) Why two times 3*y in the last line, rather than [2*y,3*y]? (this issue being of course quite likely a consequence of the first one). This behaviour can be compared with the following:

nonIdMaps := select(f -> f(y) <> y,[x -> x,x -> 2*x,x -> 3*x]):
nonIdMaps,map(f -> f(y),nonIdMaps);

the output of which I do understand, being as I expected it to be. I guess that there are some scoping rules I do not understand, or what?

how would you interpret the solutions to this:

>int(sin(y/2)^2/(x*(x-y)*y^2), x=omega__ir*t..omega__c*t) assuming t::positive, omega__ir::positive, omega__c::positive, omega__c>omega__ir;
 

which leads to the expression shown in the screen shot. In particular, I'm interested in the condition for the solution to be "undefined"

thanks.

If I make a single plot it will always be located in the centre of the worksheet. Is there an option to place it at the left border?

Dear friends,

I have to solve the BVP of the following type:

(x-1)*y''(x)+y'(x)=1+x, y(0)=1, y(1)=1

Expressing the highest derivative (y''(x)), we get a singularity at x=1.

So, as recommended, the method bvp[middefer] (or bvp[midrich]) is used:

dsolve({(x-1)*diff(y(x), x$2)+diff(y(x),x) = 1+x, y(0)=0, y(1)=1}, type = numeric, method = bvp[middefer], y(x), 'output' = Array([seq(k/10, k=0..10)]), 'abserr'=1.0e-3, 'maxmesh'=100)

Maple generates the following error:

Error, (in dsolve/numeric/bvp) unable to achieve requested accuracy of 0.10e-2 with maximum 100 point mesh (was able to get 0.82e3), consider increasing `maxmesh` or using larger `abserr`
But as I increase maxmesh, the achievable accuracy (reported in "(was able to get XXX)") decreases:

for

maxmesh = 200: 0.19e4

maxmesh = 500: 0.54e4

maxmesh = 1000: 0.12e5

maxmesh = 5000: 0.73e5

and so on.....

How to solve this equation with desirable accurancy and usage of Array as output?

i want to solve an ode , but maple return an integral in result, how can i have an answer?

Download dsolve.mw

 Dear Maple users,

In Maple 18, I want to  label y axis as $\hat{\sigma}_y$.

labels = [x, sigma[y]] works fine but I have no idea how to put a hat on sigma[y] .

regards,

Using Tools -> Check for Updates, I have just tried to update my Maple installation from 2017.0 to 2017.1. The download itself went without a hitch, but then nothing happened. In view of the fact that I clicked a button titled 'Download and Install', I would certainly expect the installation to have started automatically after download. Are anyone else experiencing the same odd behaviour?

PS: Related question of mine is Automatic update of help pages?

Limit of function f(x)=[arcsin(x)]/tan(πx/2).  At point x=1

I can't take the inverse laplace transform of one kind of functions.

Would you like to help me?

Thanks.

hello,

i went to plot a complex numerical solution , i used odeplot but did not work

please help

Thank you very much 

Download mapleprime.mwmapleprime.mw

I created a loop to calculate, using random numbers, the probability of a die roll. I got 0, which I originally attributed to the fact that the probability might have just been that low, but in comparing it to a binomial distribution, it shouldn't be 0.

I tried editing the loop to do a coin toss instead, where the probability is 0.5, and that worked fine. So I don't think my loop structure is necessarily wrong. But perhaps I wrongly input getting a 0.167 probability somehow.

Any advice would be appreciated!

dierollfail.mw

https://drive.google.com/file/d/0Bxs_ao6uuBDUNmd5ZVJtX29GT3c/view?usp=sharing
https://drive.google.com/file/d/0Bxs_ao6uuBDUSUdHSTcwSEQtS3M/view?usp=sharing

would like to return K map of P1

Summation expression for logic only consider 1 but how about wildcard x ?

if consider wildcard x as 1 too, then will use below

source = [[0,0,1,0],[0,0,1,1],[0,1,0,1],[0,1,1,0],[0,1,1,1],[1,0,0,0],[1,0,0,1],[1,0,1,0],[1,0,1,1],[1,1,0,0],[1,1,0,1],[1,1,1,0],[1,1,1,1]];
i use Quine Mccluskey algorithm

got result below

Hi, friends

I need to calculate the double integral over a non-rectangular domain.

Say, the domain is the triangle (in red)

When I enter

int(int((x^2+y^2)*`if`((y-x-1/2 <= 0) and (y+2*x-2<=0) and (y+x/2-1/2>=0), 1, 0), x=0..1, numeric = true), y=0..1, numeric = true);

or 

int(int((x^2+y^2)*eval(`if`((y-x-1/2 <= 0) and (y+2*x-2<=0) and (y+x/2-1/2>=0), 1, 0)), x=0..1, numeric = true), y=0..1, numeric = true);

an error occur (Error, (in int) cannot determine if this expression is true or false: y-x <= 1/2 and y+2*x <= 2 and 0 <= y+(1/2)*x-1/2)

For me, it is desirable to write boundary conditions in the int operator itself, not as a separate expession.

Regarding my recent question http://www.mapleprimes.com/questions/221909-How-To-Extract-Data-From-Implicit-Function I would like to share an interesting observation. Here the code of the program:

restart;
R0 := ln(y)+Re(Psi(1/2+(2*(p^2+(1/2)*sqrt(2*I+4*ksi_fs^2*p^2)*tanh(sqrt(2*I+4*ksi_fs^2*p^2)*x)/(tau+0.5e-2*a)))/y))+gamma+2*ln(2)
tau:= 10.000:ksi_fs:=10:p:=0.037:
R0p:= unapply(R0, [a,x]):
R0f:= proc(a,x)
local r:= fsolve(R0p(a,x), y= 0..1);
   `if`(r::float, r, Float(undefined))
end proc:
M:= Matrix(
   (100,100),
   (i,j)-> R0f(i, 1 + (j-1)*(0.5-0)/(100-1)),
   datatype= float[8]
);

After approximately 2 hours of calculations I get a message window

But I repeat this calculations on another computer with the same Windows 7 64 bit and Maple 17 I don't get such error and I obtain desired data.

So can Maple be sensitive to the hardware?