MaplePrimes Questions

Hi!

There is some procedure/function to convert C code into maple code? For instance, the above text file

C_code.txt

contains the C code of this paper  http://www.dcs.bbk.ac.uk/~jkl/pubs/JL1_00a.pdf to compute the image of a point in [0,1] under the N-dimensional Hilbert curve and vice versa (i.e., given a point P in the N-dimensional cube [0,1]^{N} find the point t in [0,1] such that t is mapped into P under the Hilbert curve)

Unfortunately, I don't know anything about the C programming language.

Many thanks in advance for your comments.

Fyi, there seems to be some problem here

Maple 2020.2 with Physics 897

restart;
interface(warnlevel=4):
kernelopts('assertlevel'=2):
eq:=exp(x)*sin(y(x))-3*x^2+(exp(x)*cos(y(x))+(1/3)/y(x)^(2/3))*(D(y))(x) = 0;
timelimit(30,solve(eq,y(x)));

 

Full screen shot:

 



Maple Worksheet - Error

Failed to load the worksheet /maplenet/convert/solve_error.mw .
 

Download solve_error.mw

Hi,

I noticed that, in Maple 2020.2, the caracters seem smaller. As if the zoom had somewhat been reduced (a bit).

However, in the preferences, the default zoom level I would like is between 100 and 125% (something like 110%) (since the default zoom level is adjusted by steps of +/- 25%). I wondered if there was a way to set the default zoom level to an arbitrary value. In fact I thought it would be great to have a field instead of a list of choices, so we can choose a custom value.

Thank you

I was trying to plot a simple degree two curve but with one point removed. My first attempt was the following;

p1 := plot(x^2 - 1, x = -2 .. 2);
p2 := plot([[0, -1]], style = point, symbol = circle, symbolsize = 20);
plots[display](p1, p2);

But the curve line is shown even inside the circle of the removed point. Changing order of `p1` and `p2` in `plots[display]` doesn't make any changes on the output.

My second attempt was the following.

p3 := plots[display](plottools[disk]([0, -1], 0.1, color = white)):
plots[display](p1,p3);

This didn't help either.

Is there a way to tell Maple to compute an integral over a domain defined by an implicit condition?

A trivial example would be: integrate 1 over the 2D domain defined by x^2+y^2<=1.

I know it's possible to write the explicit double integral

int(int(1,y=-sqrt(1-x^2)..sqrt(1-x^2)),x=-1..1);

Or even as a single integral:

integrate(2*sqrt(1-x^2),x=-1..1);

However, it's not always possible to do this explicitly, depending on the form of the relation f(x,y)=0 defining the domain.

 

My idea was:

int(Heaviside(1-x^2-y^2),[x=-1..1,y=-1..1]);

But Maple returns 0. However, evalf/Int returns the correct numerical value of Pi.

 

Hi,

Is there a way to keep the fractional form of probabilities? I tried with InertForm without success. thanks

ARBREprobabilité.mw

By the code

P := plot( [ sin(x)-x+(x^3)/3! ] ) :
L := plots[textplot]( [ 3 , 15 , sin(x)-x+(x^3)/3! ],  axes = none) :
plots[display]( P ,L, axes = normal )

I'd like to put the text sin(x)-x+(x^3)/3!  not  sin(x)-x+(x^3)/6   in the image.

I thought  that parse can do that

parse("sin(x)-x+(x^3)/3!")

But One use it in plots[textplot] , it is not useful!

P := plot( [ sin(x)-x+(x^3)/3! ] ) :
L := plots[textplot]( [ 3 , 15 , parse("sin(x)-x+(x^3)/3!") ],  axes = none) :
plots[display]( P ,L, axes = normal )

How to do? Thanks!

 The code

s:=solve(sin(x)=3*x/Pi,x)

gives us following output:

s := RootOf(-sin(_Z)*Pi + 3*_Z)

The allvalues command attempts to find symbolic representations of the roots using solve.
But  the code:

allvalues(s);
solve(sin(x)=3*x/Pi,x,AllSolutions)

gives us 

RootOf(-sin(_Z)*Pi + 3*_Z, 0.5235987756), RootOf(-sin(_Z)*Pi + 3*_Z, -0.5235987756), 0

RootOf(-sin(_Z)*Pi + 3*_Z)

To see the roots of sin(x)-3*x/Pi   we use plot

plot(sin(x)-3*x/Pi,x=-100..100)

 

plot(sin(x)-3*x/Pi,x=-Pi/4..Pi/4)

And we can also figure out  three roots of this function are 0  Pi/6 and -Pi/6

High probability it has no other root.

seq(eval(sin(x)-3*x/Pi,x=i),i in [-Pi/6,0,Pi/6])

0, 0, 0

Why doesn't Maple do anything about it

 

 

 

Why doesn't the graphs of alpha=0 and alpha=1  appear in the following code?

restart:
v:=t->t:
plot([seq(fracdiff(v(t), t,alpha),alpha=-1..1.5,0.5)],t=0..10,view=[0..9.5,0..5],legend=[seq('alpha'=alpha,alpha=-1..1.5,0.5)],color = [red, blue, green,yellow,cyan,magenta],axis[2]=[gridlines=[linestyle=dot]]);

 

if alpha=1;

fracdiff(t, t,alpha)

gives 1. But it doesn't appear in the figure. 

if alpha=0, 

fracdiff(t, t,alpha)

gives t. But it doesn't appear in the figure, also. 

How can i remove a section envelope ( the initial arrow and the vertical line) without removing the content.

In other words how can I liberate the content from being imprisoned in the section

 

Thank you

Hi,

I would like to create an animation of the solutions to a differential equation, but I can't get animation to work.  I copy and pasted

plots[animate]( plot, [A*sin(x), x=0..10], A=0..2 )

into maple, but the animation did not animate, and only plotted the result for A = 0.  I am using Maple 2019.  Any ideas?

Hi,
I see more and more contributions where the content of the mw file is replaced by a code snippet and, possibly, an image as illustration.
Do we have to consider this as the new norm to post question and to submit replies or answers?

(this question is related to the one Carl Love posted a few days ago  Why can't I display any worksheet? and which, if I'm not mistaken, has not been definively answered)

restart:
nuhf:=0.294*10^(-6):
Rehf:=Vhf*H/nuhf:
Vhf:=0.5:
rhohf:=965.31:
Lhs:=2.5*10^(-3):
DP1:=f1*Lhs*rhohf*Vhf^2/(2*H):
f1:=4*18.3/Rehf:
Whs:=1:
mhf:=rhohf*Vhf*Whs*H:
Rehf:=Vhf*H/nuhf:
PL1:=DP1*mhf/rhohf:
DP2:=f2*Lhs*rhohf*Vhf^2/(2*H):
f2:=0.3164/(Rehf^(0.25)):
PL2:=DP2*mhf/rhohf:
procd:=proc(H)
    if Rehf<1000 then PL1 elif Rehf>1000 then PL2 else 0 fi;
   end;

plot('procd(H)',H=0..0.002);

When doing solve(res,x); maple returns back x

Does this means the equation is true for any x?

Also, doing PDEtools:-Solve(res,x) returns nothing.

I was trying to check if my solution is valid for an ode, and I obtained res above is what odetest() gives back, I wanted to find for what could res be zero.

Here is the code

restart;
ode:=diff(y(x),x)=2*sqrt(1+y(x))*cos(x);
my_sol:=y(x)=sin(x)^2+2*sin(x);
res:=odetest(my_sol,ode);
res:=simplify(res)=0;
solve(res,x);

And now 

PDEtools:-Solve(res,x)

gives nothing.

So I am a little confused what is going on. does solve result mean the equation is true for any (I think the solution I have is correct, so may be what this means,  but wanted to make sure, as I do not think I've seen this before)  And if so, why then PDEtools:-Solve did not return the same result.

Maple 2020.2, windows 10, Physics 897

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