Maple 2018 Questions and Posts

These are Posts and Questions associated with the product, Maple 2018

I am having problems with the attached worksheet, in which I am attempting to solve a couple pair of PDEs, particularly in defining initial and boundary conditions.  See MapleExample1c.mw

Can anyone help?

Melvin

Hi,

I'm surprised by the result of the procedure VectorCalculus:-Curvature which is always a positive scalar quantity:
For instance
c := VectorCalculus:-Curvature(<x, sin(x)>, x):
plot(c, x=0..2*Pi) 
# c >=0 for all x in [0, 2*Pi]

In the help pages it's written that the (signed) curvature for a function y(x) is y''/(1+y' 2)(3/2).

y := sin(x):
c := diff(y, x$2) / (1+diff(y,x)^2)^(3/2):
plot(c,  x=0..2*Pi) 
# c < 0 if x in (0, Pi)  and  c > 0 if x in (Pi, 2*Pi)

Could you please help me to understand this?

Thank in advance

Hello,

How to calculate the derivative of modified Bessel fucntion of the first kind and order \alpha, such that \alpha>-1/2?

I need to calculate de general term of the derivative of modified Bessel function of the first kind and order \alpha.

 

Best regards 

Worm greeting to all

I use the following to plot two orthogonal vectors display(arrow(1,0), arrow(0,1)) as

 

  Now, I need to shift these two orthogonal vectors to another point.

In this question at here https://tex.stackexchange.com/questions/503745/how-can-i-get-correct-the-point-a-and-b-automatically-in-this-picture/503838?noredirect=1#comment1272706_503838
The points A and B lie on the circle is intersection of the sphere x^2 + y^2 + (z-3)^2 = 25 and the plane z = 0. 
How can I find coordinates of the points A and B by Maple?

 

unprotect(D); f := proc (x, y) options operator, arrow; (295849/5841396)*x^2-(29441/324522)*y*x+(33995/216348)*y^2-(5989/14751)*x+(3635/4917)*y+1 end proc; 295849 2 29441 33995 2 5989 f := (x, y) -> ------- x - ------ y x + ------ y - ----- x 5841396 324522 216348 14751 3635 + ---- y + 1 4917 coeffs(f(x, y)); -5989 3635 295849 33995 -29441 1, -----, ----, -------, ------, ------ 14751 4917 5841396 216348 324522 A, B, C, D, E, F := %; -5989 295849 33995 -29441 3635 A, B, C, D, E, F := 1, -----, -------, ------, ------, ---- 14751 5841396 216348 324522 4917

Hi,

In statistics a  "degree of freedom" is a strictly positive integer.

The three distributions ChiSquare, StudentT and FRatio from package Statistics have degrees of freedom as parameters. Nevertheless they accept any strictly positive real values for them.
(one can verify that their "Conditions" attribute is of the form [0 < n] instead of [n::posint]).

I think this ought to be corrected in future versions
 

Hello,

I have installed the Physics Package with:

PackageTools:-Install("5137472255164416", version = 329, overwrite)

I have a question about the calculation of the Tensor determinant:

I use two ways to calculate the determinant of the same matrix:

The first with Physics package and the second with LinearAlgebra Package:

It is easy to calculate analytically the result it is : -1

But Physics Package gives : +1 and LinearAlgebra gives: -1

My question is why I found +1 with Physics Package : What I doing wrong ?.

Please find my source hereafter:

**************************************************

restart

with(Physics)

Setup(coordinates = {X = [t, x, y, z]}, dimension = 4, metric = {(1, 1) = 1, (2, 2) = -1, (3, 3) = -1, (4, 4) = -1}, signature = `+---`, mathematicalnotation = true)

Define(H[mu, nu] = Matrix(4, {(1, 1) = 1+h, (1, 2) = h, (2, 2) = -1+h, (3, 3) = -1, (4, 4) = -1}, shape = symmetric))

H[]

H[determinant]

with(LinearAlgebra)

B := Matrix(4, {(1, 1) = 1+h, (1, 2) = h, (2, 2) = -1+h, (3, 3) = -1, (4, 4) = -1}, shape = symmetric)

Determinant(B)

***************************************

Thanks for your answer,

Sincerely yours

Xavier

 

Hi 

I am studying Marine Engineer, and we are gonna work alot with vectors. I am using Maple as my mathematical software and i would like to know if you can do a simple vector addition in Maple?
I have tried to make a simple vector diagram to help understand my problem. 
My vector U, is my reference vector, and my two vectors I1 and I2 are the vectors i would like to plus. I know the length of both I1 and I2, and i know the angle between I1 and U and I2 and U.

If i am using my TI-nspire, i can just type in the length and angle on both I1 and I2, to my reference vector, and then plus them together. Is this possible to do in maple?

For the vectors onmy example the result of vector additon of I1+I2 = 2.42 to an angle of 48.07 degree.

The image is just for representation and is not accurate according to the lengths and angles.

Hope someone out there can help me.

 

Let be given a cylinder with radius of the base circle is equal to 3 and the altitude of the cylinder is equal to 2. How can I draw square ABCD so that A, B and C, D lie on two base circles. How can I get one option of all vetices A, B, C, D ?

I would like to draw an ellipse by orthonal affinity of a circle. Thank you.

i want to solve the systems of diff equation what's the problem   0.mw

I calculate volume of tetrahedron SABC by this way. Now, I want to find one option  of coordinates of all vertices of this tetrahedron. How can I get the coordinates of the points S, A, B, C so that coordinates  center of circumcircle of the triangle ABC is (0,0,0)?

 

restart:
SA := 3: 
SB := 5: 
SC := 7:
AB := 3:
BC := 4: 
AC := 5:
V := (1/12)*sqrt(SA^2*BC^2*(AB^2+AC^2-BC^2-SA^2+SB^2+SC^2)+SB^2*AC^2*(AB^2-AC^2+BC^2+SA^2-SB^2+SC^2)+SC^2*AB^2*(-AB^2+AC^2+BC^2+SA^2+SB^2-SC^2)-SA^2*AB^2*SB^2-SB^2*BC^2*SC^2-SA^2*AC^2*SC^2-AB^2*BC^2*AC^2);

From here https://www.mapleprimes.com/questions/227573-How-To-Get-Coordinates-Of-Triangle-ABC
I find coordinates of the point A, B, C. Now I tried
 

with(geom3d):
point(A, -3/2, -2, 0):
point(B, 3/2, -2, 0):
point(C, -3/2, 2, 0):
point(S, x, y, z):
solve([distance(S, A) = 3, distance(S, B) = 5, distance(S, C) = 7], [x, y, z], explicit);
with(geom3d):
point(A, -3/2, -2, 0):
point(B, 3/2, -2, 0):
point(C, -3/2, 2, 0):
point(S, x, y, z):
solve([distance(S, A) = 5, distance(S, B) = 3, distance(S, C) = 7], [x, y, z], explicit);

Use the above code, I obtain the result.

Lang_2_output_as_tswitch_varies.mw

^ in this worksheet I have made a graph of a variable in a simple ODE against time (shown below), at t=150 a switch condition, in the worksheet called tswitch, changes the rates of change of the ODE.

I am thinking about afunction that maps tswitch->solution of the ODE and would like to visualise it as a 3d surface, but couldn't work it out in Maple

 

How to get correct result this equation
restart; with(Student:-MultivariateCalculus);
A := [0, 0, 0];
B := [c, 0, 0];
S := [x, 0, z];
solve([Distance(S, A) = a, Distance(S, B) = b], [x, z]) assuming and(a > 0, b > 0, c > 0);

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