## why is Maple prime main web site down for so long?...

When I click on http://www.mapleprimes.com/   I get this message

And this has been the case for few days now. But only now I can see I can access the site if I know the internal sub link to it.

So why is the main page down for so long?

## Ocean waves in Maple...

Probably not Maple's territory, but maybe a challenge?  Can we can get maple to do this?  Done by Matlab found here..

http://stackoverflow.com/questions/28279337/matlab-cuda-ocean-wave-simulation

## Distance Between 2 curves...

i got 2 curves
a := abs(x);
b := (3/4)*x^2+1/4;

how can i get the max distance between them from x = -1 until x =1?

heeeeeeeeeelp

## Want to solve system of nonlinear ODEs...

Hello! Hope everyone would be fine. I want to solve the following system of ODEs please help to find the numerical solution

N := .6; alpha := .4; beta := .1; Nt := .2; Pr := .5; Nb := .1; s := .2; lambda[1] := 1; delta := .5; gm := 1; Sc := 1:L:=1:

Eq1 := (alpha*s+1)*(diff(F(eta), eta, eta, eta))-(F(eta)+(1/2)*s*eta)*(diff(F(eta), eta, eta))+((1/2)*(diff(F(eta), eta))-s)*(diff(F(eta), eta))-2*(G(eta)^2-(1-gm)^2)-2*lambda[1]*(H(eta)+N*Y(eta))-(alpha+beta-(1/4)*delta*(diff(F(eta), eta, eta, eta)))*(diff(F(eta), eta, eta))^2-(alpha-2*beta)*(diff(F(eta), eta))*(diff(F(eta), eta, eta, eta))-(2*(alpha-beta-(1/4)*delta*(diff(F(eta), eta, eta, eta))))*(diff(G(eta), eta))^2-(2*(alpha-(1/4)*delta*(diff(F(eta), eta, eta))))*G(eta)*(diff(G(eta), eta, eta)) = 0; Eq2 := (alpha*s+1)*(diff(G(eta), eta, eta))-F(eta)*(diff(G(eta), eta))+G(eta)*(diff(F(eta), eta))+s*(1-gm-G(eta)-(1/2)*eta*(diff(G(eta), eta)))-(1/2)*alpha*s*eta*(diff(G(eta), eta, eta, eta))+((3/2)*alpha+beta)*G(eta)*(diff(F(eta), eta, eta, eta))-((1/2)*alpha+beta)*(diff(F(eta), eta))*(diff(G(eta), eta, eta))-delta*((diff(F(eta), eta, eta))^2+6*(diff(G(eta), eta))^2)*(diff(G(eta), eta, eta)) = 0; Eq3 := (diff(H(eta), eta, eta))/Pr-F(eta)*(diff(H(eta), eta))+(1/2)*H(eta)*(diff(F(eta), eta))-s*(2*H(eta)+(1/2)*eta*(diff(H(eta), eta)))+Nb*(diff(H(eta), eta))*(diff(Y(eta), eta))+Nt*(diff(H(eta), eta))^2 = 0; Eq4 := (diff(Y(eta), eta, eta))/Sc-F(eta)*(diff(Y(eta), eta))+(1/2)*Y(eta)*(diff(F(eta), eta))-s*(2*Y(eta)+(1/2)*eta*(diff(Y(eta), eta)))+Nt*(diff(H(eta), eta, eta))/Nb = 0;

IC1 := F(0) = 0, (D(F))(0) = 0, G(0) = gm, H(0) = 1, Y(0) = 1; IC2 := (D(F))(L) = 0, G(L) = 1-gm, (D(G))(L) = 0, H(L) = 0, Y(L) = 0; dsys1 := {Eq1, Eq2, Eq3, Eq4, IC1, IC2}; dsol1 := dsolve(dsys1, numeric, output = listprocedure, range = 0 .. L);

dsol1f := subs(dsol1, F(eta));

dsol1g := subs(dsol1, G(eta)); dsol1h := subs(dsol1, H(eta)); dsol1y := subs(dsol1, Y(eta));

With my best regards and sincerely.

## Bug: Definite integral of positive function is neg...

Let:

f:=x->1/sqrt(2*Pi)*exp(-x^2/2);

I.e. f is a standard Gaussian PDF.

Then (in Maple 2016.1):

Int(convert(f(x)*f(y)*x*x*abs(x+y),piecewise,x),x=-infinity..infinity,y=-infinity..infinity):
evalf(%);

Returns:

1.692568751

However (again in Maple 2016.1):

int(convert(f(x)*f(y)*x*x*abs(x+y),piecewise,x),x=-infinity..infinity,y=-infinity..infinity):
evalf(%);

Returns:

-0.5641895835

This is clearly incorrect, as the integral of a positive function must be positive.

This also seems to be a problem in which ever version of Maple is used behind the scenes on this forum.

gives:

## How do I get a recurrence relation in differentiat...

Hi, there

How can I find the recurrence relation  for second derivative of sequence of functions  f-{n}(x)=\frac{(1-x^2)^n}{n!} in  maple 15?

we know the solution f"_{n}(x)=2(1-2n)f_{n-1}(x)+4f_{n-2}(x)

Regards

M.R. Yegan

## how to run maple code in matlab? ...

Dear all

I have created a script code in maple. I also have contructed a power circuit in matlab simulink. How I use my code in matlab?

## too many levels of recursion...

Hi,

Seem to be a bit stuck. Here's my code:

## How to simplify this hypergeometric function?...

It is suggested

hypergeom([1/3, 2/3], [3/2], (27/4)*z^2*(1-z)) = 1/z

if z > 1. Here is my try to prove that with Maple:

 (1)

 (2)

 (3)

## Vectorization of Symbolic Functions...

Maple provides efficient vectorization and automatic parallelization for many common operators. For example

x -> 2*~x*~cos~(x*~x)

But in my application it is common to want to create rather long vectorized operators starting from some complicated symbolic computations. Doing conversions by hand from symbolic expressions to element-wise operations is laborious and error prone.

As a very simple example consider that it is possible to obtain (almost) the same result as above by writing the following as a vectorized operation

D(x->sin(x^2))~

But there are at least two problems with this. First of all it is not nearly as efficient as the first operator and second, perhaps not unrelated, is that the datatype returned when applying this operator to a Vector/rtable of hardware floats (e.g. datatype=float[8]) becomes something  more general.

My question is how can I convert a complicated symbolic expression into an efficient numeric element-wise vector operation?

I have tried several different approaches but so far without success. In the case above for example it seemed natural to expect that the following derivative

D(x->sin~(x^~2))

would produce a vectorized result, but this is not the case. In another attempt I was unable to see how to perform substitions into an expression, e.g. like this

unapply(subs(*=*~, cos=cos~, diff(sin(x),x)), x)

I would be glad to receive suggestions and/or references to relevant documentation.

## Clock elapsed function , how to run it more times ...

I use the example procedure when search. Clock in help

but elapsed function can only run one time

because it return clock is not running

need to run clock start again and calculate from beginning again

how elapsed function can run more times

## Fractional order non linear system...

Hi!

Everyone,

I want to draw  phase plane of system of three fractional order equations.

Note that

Also want the  phase portrait when the values of alpha are not same....

Also

Thanks

## solve a system of 3 equations...

I want to get solutions of this system ,can anyone help me ?solutions.mw

## Boundary value problem...

(1)How can i draw a graph by considering eta on x-axis and f'(eta),theta(eta)on y-axis in a single graph with respect to variatiation  in the parameter beta=0.01,0.1,1.0..

(2). how can i get different values of f'(eta) by varying values of eta .

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 (2)
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 (3)
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## How to plot function(r(theta), theta) in polar coo...

I am trying to plot f=[r^2 *cos(theta)+r*sin(theta)],as a DensityPlot[] in polar coordinates.

here r is a function of theta, r=r1(θ)..r2(θ) , for this reason, I have a problem to plot f in density plot

f=[r^2 *cos(theta)+r*sin(theta)];

r1(theta)= 0.3+0.1*cos(theta);
r2(theta)= 0.5+0.1*cos(theta);

display(changecoords(densityplot(f, r =r1(theta)..r2(theta), theta = 0 .. 2*Pi, style = patchnogrid, colorstyle = HUE), polar), axes = box, orientation = [270, 0], labels = [x, y, ]);

(Error, (in plots/densityplot) bad range arguments r = .3+.1*cos(theta) .. .5+.1*cos(theta), theta = 0 .. 2*Pi )

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