howdy.

evalf(map(log10,[25,5,1,10,4,20]))=

[1.39794000867203, .698970004336017, 0., 1., .602059991327960, 1.30102999566398]

How do I reverse this process , ie get back [25,5,1,10,4,20] using map command. Obviously it's 10 to the power but map(10^,[1.39794000867203, .698970004336017, 0., 1., .602059991327960, 1.30102999566398]) won't work

I'd like to plot the following inequalities:

sqrt(x)<=1/sqrt(2)

1/sqrt(2)<sqrt(x)<=1/sqrt(2)

Hey!

I have this MATLAB script, but as I work in Maple, I'll need to translate it to Maple. 
I know how to define symbols and functions, but I don't know which Maple commands to use, of if it needs to be done in another way, so the problem is translating from " dZ = [dx; dy; ax; ay; dm];" and down.

Any help would truly be greatly appreciated! Thank you!  

This is the script:

function dZ = meteor_step(~, Z)

  P = 1.2; % initial atmospheric pressure
  H = 1.39E-4; % scale height of atm pressure
  E = 8.11131859E6; % evaporation energy
  D = 1; % drag constant
  G = 9.814; % acceleration due to gravity
  PM = 3.3E3; % density of the meteor
  
  S = 3.986E14; % standard gravitational parameter of Earth (G*M)
  R = 6.3674447E6; % radius of the Earth (meters)

  x = Z(1);  
  y = Z(2);
  dx = Z(3);
  dy = Z(4);
  m = Z(5);
  
  atm = P*exp(-y*H);

  v = sqrt(dx^2+dy^2);

  area = pi * ( (3*m)/(4*PM) )^(2/3);

  dist = sqrt(x^2+y^2);
  Gv = -9.8;

  accel = -(D*atm*area)/m*v;
  ax = accel * dx;
  ay = accel * dy + Gv;
  

  dm = -(atm*v^3*area)/(2*E);
  
  dZ = [dx; dy; ax; ay; dm];
  
end

[t, R] = ode45(@meteor_step, [0 250], [0, 100000, 100, -300, 25]);

x = R(:,1);
y = R(:,2);

dx = R(:,3);
dy = R(:,4);

v = (dx.^2+dy.^2).^(1/2);

m = R(:,5);

figure(1);
plot(t, y);
  title('Meteor Kinematics: Height vs Time');
  xlabel('Time elapsed (s)');
  ylabel('Height (m)');

figure(2);
plot(x, y);
  title('Meteor Kinematics: Horizontal vs Vertical Position');
  xlabel('Horizontal (m)');
  ylabel('Vertical (m)');

figure(3);
plot(t, v);
  title('Meteor Kinematics: Speed vs Time');
  xlabel('Time elapsed (s)');
  ylabel('Absolute speed (m/s)');

figure(4);
plot(t, m);
  title('Meteor Kinematics: Mass vs Time');
  xlabel('Time elapsed (s)');
  ylabel('Mass (kg)');

  
figure(5);
plot(t, dy);
  title('Vertical Velocity vs Time');
  xlabel('Time elapsed (s)');
  ylabel('Vertical velocity (m/s)');

temp = abs(y - 52900);
[~, index] = min(temp);
  
t(index)
dx(index)/1000
dy(index)/1000

I've got a worksheet in which I have invested many hours of CPU execution time and if the computer goes down, or Maple fails for some reason, I'll lose it all.

If this happens I would like to be able to continue the calculation from where I left off.

By saving the worksheet periodically, I can save all the commands, but not the results, so if I have to restart, I'll have to wait many hours before the worksheet catches up to where it left off.

In ancient versions of Maple, you used to be able to save an executed worksheet including results (I sort of remember that you wrote a file with the extension ".M")  but the new help pages say that is now different from what it used to be. Obviously I can "save" individual symbols to a file, but for a complicated worksheet  that gets complicated.

I've read about "maplet" files, but that doesn't seem to fill the bill either.

So, is there any simple way to save a worksheet so you can continue seamlessly from where you left off after a crash, with all the previous results intact?

I have written a program which plays the game of Multicube, a commercially made boardgame. It works OK except that when the game is replayed, the previous game output stays on the screen.  This is rather distracting and I'd like the screen cleared when a new game is run.   I'd like to know how the screen previous ouput can be cleared.   ...or what is the likely cause.

   At the start of my program I have:

restart;
interface(echo=0, verboseproc=0, warnlevel=0, prettyprint=1):

#I thought restart; would automatically have cleared any previous output.

The program reads necessary input (eg no of players, ..)  using:

x:=readline(terminal):

Thanks,  David

Hello,

I am trying to solve the boundary value problem (1-x^2)*y'' - 2*x*y' +12*y = 0 with y(-1) = -1 and y(1) = 1.  I have not used Maple much, but from some web surfing, it seems like the following inputs should work:

de := (1-x^2)*(diff(y(x), `$`(x, 2)))-2*x*(diff(y(x), x))+12*y(x) = 0

Y := dsolve(de, y(-1) = -1, y(1) = 1)

However, when I input these lines, I get the error: Error(in dsolve), found wrong extra argument(s): y(-1) = -1, y(1) = 1

Does this mean that Maple can't solve this problem?  Is my syntax wrong?  I would appreciate any help.

Thanks!

Tim

I have the following situation:

HB:=Bend(L,a,n);

Bend is a proc, that returns a Record with info based on its parameters. I would like to get access to the name I assign to (i.e. HB) in the proc. Any chance?

Mac Dude

PS: I can of course kludge things by adding an argument to the proc Bend. But I'd like to avoid that.

Hi,

I'm trying to solve the following differential equation numerically with dsolve:

but dsolve gives me this error:

> res := dsolve(DGL, numeric, parameters = [y0, A, B, C, E]);
Error, (in DEtools/convertsys) unable to convert to an explicit first-order system

I think the problem is that I use the wrong solver. Does Maple provide a solver which is capable of solving this kind of equations (nonlinear ODE)?

Thanks in advance!

Hi,

For my thesis I would like to illustrate the inclination of the solar system objects in a plane. Imagine the Solar system as a circular plane which is the average of the motions of all objects orbiting the Sun. Each individual planet/object is inclined towards this averaged plane - some more, some less. E.g. this image. Behind Neptune there lies the so-called Kuiper belt with many thousands of dwarf planets (Pluto is one of them and there are over 1000 objects known out there already). Now imagine that the big heavy Jupiter and other big planets perturb those small objects out there: so they are also inclined towards the average plane, see this image. Their inclination depends on their radial distance to the Sun (measured usually in Astronomical Units...1 unit is the distance Sun-Earth...we are talking about 40 to 50 units here). For one, I want to visualise this: imagine a circular plane and each orbit out there has another angle to the average plane. This is the first. But now: imagine the circle with it's 360°. Each object reaches it's highest point on its orbit around the Sun on another angle on this 360° circle. Neptune e.b. at 170°, Pluto at 250° etc. You get the picture. So not only are the objects in the Kuiper belt inclined differently, but their maximum orbit positions are also scattered across an imaginary 360° circle. I want to show this with a 3d-plane like this image but not with two peaks for one orbit. Is there a way to do/plot/visualise this in Maple? I am just interested in a visualisation of the principle without any empirical data behind this.

Thanks.

hello , to solve a differential euqations , maple gave me this error. please help me.

TG.mw

Hi all,

I'm trying to initialize a 4-vector and promote it as a tensor in Maple 16 using the Physics package. My attempt so far has been unsuccessful :) 

This 4-vector needs to be a function of the coordinates X. What I'm trying to do is to allocate terms by terms my tensor as indicated in my attempt below. Everything looks fine (the query is telling me F2 is a tensor) but when I'm trying to compute contravariant quantities, I can't obtain an answer for a given coordinate (here F2[~n](X) is not equal du v_1(X))... Finally, the last line, computing the sum over all the indexes is not giving me an answer... 

restart; with(Physics):
Setup(mathematicalnotation=true):
Setup(coordinatesystems = cartesian):
Define();
g_[]:

F2[1]:=(x,y,z,t)->v_1(X);F2[2]:=(x,y,z,t)->v_2(X);F2[3]:=(x,y,z,t)->v_3(X);F2[4]:=(x,y,z,t)->1;

Define(F2[mu](X));

Define(F2,query);

F2[1](X);F2[2](X);

F2[~1](X);F2[~2](X);

F2[~nu].F2[nu]

Surely, something is wrong in my way of defining a spacetime tensor. What would be the solution to obtain a decent contravariant F2?

Another more or less related question would be to know how to compute a taylor expansion of a function itself i.e. 1/(1+f(X))~ 1-f(X) since f<<1? Would there be a built-in fonction to do such a thing?

Many thanks!

Vincent

Hello people in mapleprimes,

I hope you will give an answer to my following question.

This is a question of nonunit(algebraic) in patmatch.

In help page of maple this examples are on.

Case i)

>patmatch(a, A::(nonunit(algebraic))+B::(nonunit(algebraic)), 'la');

false

Case ii)

>patmatch(a,A::(nonunit(algebraic))+B::algebraic,'la'); la

ture

[A=a,B=0]

Is unit in the case of sum zero, so that in Case i) false is shown, though in Case ii) B=0 is returned?

Best wishes.

taro

Dear people in mapleprimes,

>define(INT, linear, conditional(INT(a::algebraic, X::name) = a*X, _type(a, freeof(X))), INT(X::name, X::name) = (1/2)*X^2);

>INT(2*x+4, x);

x^2 + 4*x

>INT(z+x, z);

(1/2)* z ^2+ x*z

is written in the help page of maple.

This code is to make a function INT.

What it means is that if INT(a::algebraic, x::name) then this is transformed into a*X, where a is independent from x.

And, INT(X::name,X::name) is transformed into (1/2)*X^2.

The first of what I want to ask you is the way of use of "_type", which is not in the help page, and as for names with "_" ahead, 

it is written that "_" means internal command for Maple, so not to use it. Is it right to use a name with "_" ahead of it here?

The second of what I want to know is the way to use "conditional."

Please teach me the meaning of this.

Thanks in advance.

I hope you will teach me the above questions.

Best wishes.

taro

seq(i,i=1..5);  gives output 1,2,3,4,5

seq(i,i=5..1);  seems to get ignored in Maple 7.  It does not return an error message.

I was hoping to step back from a large number to a smaller one in stepsof minus one.  The for loop structure allows negative "increments" - so I experimented by putting the decrement value of -1 between the two dots.  I was expecting it to givean error message, so was surprisd when it gavesome output!

eg  seq(i, i=5.-1.2);  gives output of 38, -1

I'm curious as to what is happening here?  Also, has the seq command been upgraded in later versions of Maple?  eg is it possible to do negative decrements?

Hi there,

I would like to know whether there is some way to print non-integer axis numbers for a given plot.

Let's say I have an array for an independent variable such as [0.5 1 1.5 2]. I would like Maple to use these values in the corresponding axis instead of printing the array indices [1, 2, 3, 4].

I would like to know how this is done for a surface plot.

Attached is the worksheet where "b" is such a parameter/independent variable: MapleSimulation_test11.mw

Thank you,

jon