MaplePrimes Questions

hi, learners of maple like me, i was handling a project,but i came across this problem,and i began to doubt the accuracy of maple-plot,,,

very simply expression,result3,changing with the parameter f,

i first plot the f from 100 to 5000,

than i need to watch closer,

so i change the define domain of parameter f, plot f from 100 to 1000,  

and the result of plot definitely  differs from the previous one. 

low vally in the first figure (f in the scale of 100-1000),disappears! that's insane...

 

you can see below,

anyone see it, can you give me some clue? i really do not understand this. why ,why why,,

result3 := 3.269235506947450*10^11*sqrt(-1/(0.975698207102e-3*cos(0.19042716640833e-1*f)^2*cos(0.9521358320417e-2*f)^4-0.975698207102e-3*cos(0.19042716640833e-1*f)^2*cos(0.9521358320417e-2*f)^2+5.099915851388520*10^(-8)*cos(0.9521358320417e-2*f)^4-5.099915851388520*10^(-8)*cos(0.9521358320417e-2*f)^2+1.311634114532540*10^12*sin(0.19042716640833e-1*f)*sin(0.9521358320417e-2*f)*cos(0.9521358320417e-2*f)*cos(0.19042716640833e-1*f)+4.405792916762340*10^26*cos(0.19042716640833e-1*f)^2-4.406861706842330*10^26))

326923550694.745*(-1/(0.975698207102e-3*cos(0.19042716640833e-1*f)^2*cos(0.9521358320417e-2*f)^4-0.975698207102e-3*cos(0.19042716640833e-1*f)^2*cos(0.9521358320417e-2*f)^2+0.509991585138852e-7*cos(0.9521358320417e-2*f)^4-0.509991585138852e-7*cos(0.9521358320417e-2*f)^2+1311634114532.54*sin(0.19042716640833e-1*f)*sin(0.9521358320417e-2*f)*cos(0.9521358320417e-2*f)*cos(0.19042716640833e-1*f)+0.440579291676234e27*cos(0.19042716640833e-1*f)^2-0.440686170684233e27))^(1/2)

(1)

plot(result3, f = 100 .. 5000);

 

 

plot(result3, f = 100 .. 1000);

 

 

 

``


 

Download test.mw

 

 

 

doubt.mw

Equation21v2.mw

 

Hi,

When I do the derivation of a summation in order to one single term should not the result come out of the summation in the example attached in the file doubt? for example the derivative should not have yielded Ci and not the summation of Ci because for example if want the derivative in order to y1 it should be only C1 and not the summation of Ci.

 

The same happen when I go to a more complex case like in the file Equation21v2, should the result in the last double summation before T drop the summation over i to NC?

 

Many thanks in advance for your help!


 

Hi,

 

I have a problem of having a problem to solve the following equation with the this error. I found out that it might be due to that I have a differential that is squared and maple could not calculate it as after square root it will have positive and negative. May I know how to overcome this other than changing my equations?

ODE_summarize.mw
 

restart; with(DEtools)

````

sol1 := alpha*(diff(f(y), y, y, y)) = -(1/4)*f(y)*(diff(f(y), y, y))*n+(1/2)*(diff(f(y), y))^2*n-(3/4)*f(y)*(diff(f(y), y, y))+(1/2)*(diff(f(y), y))^2-g(y), diff(g(y), y, y) = -(1/4)*P[r](f(y)*(diff(g(y), y))*n-4*n*(diff(f(y), y))*g(y)+3*f(y)*(diff(g(y), y)))

alpha*(diff(diff(diff(f(y), y), y), y)) = -(1/4)*f(y)*(diff(diff(f(y), y), y))*n+(1/2)*(diff(f(y), y))^2*n-(3/4)*f(y)*(diff(diff(f(y), y), y))+(1/2)*(diff(f(y), y))^2-g(y), diff(diff(g(y), y), y) = -(1/4)*P[r](f(y)*(diff(g(y), y))*n-4*n*(diff(f(y), y))*g(y)+3*f(y)*(diff(g(y), y)))

(1)

bc := (D(f))(y)

(D(f))(y)

(2)

gg := convert(bc, diff)

diff(f(y), y)

(3)

gg1 := limit(gg, y = infinity)

limit(diff(f(y), y), y = infinity)

(4)

gg2 := convert(gg1, D) = 0

limit((D(f))(y), y = infinity) = 0

(5)

gg2

(D(f))(y) = 0

(6)

bc1 := eval(f(y), y = 0) = 0, eval((D(f))(y), y = 0) = 0, convert(gg1, D) = 0, limit(g(y), y = infinity) = 0, eval(g(y), y = 0) = 1

f(0) = 0, (D(f))(0) = 0, limit((D(f))(y), y = infinity) = 0, limit(g(y), y = infinity) = 0, g(0) = 1

(7)

``

odesub1 := eval(eval(sol1, n = .6), P[r] = 0)

alpha*(diff(diff(diff(f(y), y), y), y)) = -.9000000000*f(y)*(diff(diff(f(y), y), y))+.8000000000*(diff(f(y), y))^2-g(y), diff(diff(g(y), y), y) = 0

(8)

sol2 := dsolve({bc1, odesub1}, numeric, [f(y), g(y)], output = operator, continuation = alpha, initmesh = 2400, method = bvp[midrich])

Error, (in dsolve/numeric/bvp/convertsys) unable to convert to an explicit first-order system

 

``


 

 

 

 

 

 

 

 

 

 

Hi Guyz 

I have a problem with a numerical solution.

with the boundary conditions mentioned in the file we want to solve the differential equation numerically and find omega by using the shooting method

numshooting.mw

i want to know how  to save a  a constant of a funcition as a variable.

for example:
eq:=x=1-3*t

i want to save 3 as variable
c:=3

I have a workbook that derives the Cobb-Douglas factor demand functions:

The final formulas (10) and (11) are not in the same format as the formulas in my textbook (by Hal Varian). In fact my last formulas betray no obvious symmetry while Varian's forms do.

Download cobb-douglas.mw

Here is a picture of them scraped from the text.

 

Is it possible to instruct Maple to obtain these forms?

Maple 17 is very exciting so I am hopeful ....

P.

 

Hi everyone,

Instead of writing:

a[1] < b[1] or (a[1] = b[1] and a[2] < b[2]) or (a[1] = b[1] and a[2] = b[2] and a[3] < b[3]) or (a[1] = b[1] and a[2] = b[2] and a[3] = b[3] and a[4] < b[4]) or (a[1] = b[1] and a[2] = b[2] and a[3] = b[3] and a[4] = b[4] and a[5] < b[5])...

Is there a more convenient way to do so? Plus, what if a[1] = b[1] and a[2] = b[2] and ... and a[99] = b[99] and a[100] < b[100]? I do not imagine writhing everything.

Thanks for your help. 

In the below calculations, I get some solutions after solving the system. I am not sure if this is done assuming that all the values that are under the radicals are positive or indeed they are positive without further assumptions. I mean can I be sure that each given set of solution is a feasible solution? I suspect that Maple may ignore the assumptions sometimes.  

Please, can someone give me a hand? I can not understand why in the first case the collect command does not work while the second one works correctly. Many thanks for your attention.trasformaziione_equazioni1.mw
 

esp1 := -a^4+a^2*c^2

-a^4+a^2*c^2

(1)

esp2 := collect(esp1, a^2);

This, apparently, does not work properly

-a^4+a^2*c^2

(2)

esp3 := collect(-a^4+a^2*c^2, a^2);

-a^4+a^2*c^2

(3)

esp11 := -a^2*x^2-a^2*y^2+c^2*x^2

-a^2*x^2-a^2*y^2+c^2*x^2

(4)

esp12 := collect(esp11, x^2);

(-a^2+c^2)*x^2-a^2*y^2

(5)

``


 

Download trasformaziione_equazioni1.mw

 

The following are the equation and plot3d of the minimal surface named Catalan:

Catalan := [alpha-sin(alpha)*cosh(beta), 1-cos(alpha)*cosh(beta), 4*sin((1/2)*alpha)*sinh((1/2)*beta)]
plot3d(Catalan, alpha = 0 .. 2*Pi, beta = -3 .. 3, scaling = constrained, title = "Catalan's surface", titlefont = [Courier, bold, 14])

I would like to color and thicken the edge of this surface to emphasize what I presume is the wire which frames the soap film which forms the surface.

Contourplot3d only shows contours at constant values of the z coordinate, however the plot3d display with style option "surface with line" clearly shows the surface's edge contour, among others.

Given the surface equation, is there any way to display the surface edge programmatically e.g. as a spacecurve? 

How to manually switch frames in the DifferentialGeometry package? (Example: Help_Differential geometry_lesson2_exercise 4). Thank you

Without my knowingly changing any Maple parameters, the execution time values of variables appearing in the window displayed when a DEBUG statement is executed have recently started to be listed at the end of my worksheet.

If I have been doing extensive debugging this list can be quite lengthy and a nuisance to erase.

Why did this listing suddenly begin and how can I stop it?

The following construction of a simple vector of matrices (just a test example)

Vector(2,(a) -> Matrix(2,2,(b,c) -> m||a||b||c));

works in Maple 17, but not in Maple 2017 where the error message "Error, (in Vector[column]) number of elements on right side must match subselection on left side" is produced. Why that?

Update: If no output is prompted, i.e., if the above line is terminated with colon instead of semicolon, then no error is raised. What?!

Hi;
what's the difference between "assuming" and "assume" commands in maple? tell me this problem with example. Thanks.
with regards...

 I'm thinking upload a technical paper into maple cloud, and i would like to keep the intellectual property of this paper or have a mention from the reader if they use it. Is it possible?. Thanks!

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