Hi. I want to solve this system of equations by varying the value of n. I managed to aolve and plot for n=1, 1.1 and 1.2 but it happens to be a problem when I let n=1.3.

>restart;

>Digits := 15;

>with(plots):n:=1.3: mu(eta):=(diff(U(eta),eta)^(2)+diff(V(eta),eta)^(2))^((n-1)/(2)):

>Eqn1 := 2*U(eta)+(1-n)*eta*(diff(U(eta), eta))/(n+1)+diff(W(eta), eta) = 0;

>Eqn2 := U(eta)^2-(V(eta)+1)^2+(W(eta)+(1-n)*eta*U(eta)/(n+1))*(diff(U(eta), eta))-mu(eta)*(diff(U(eta), eta, eta))-(diff(U(eta), eta))*(diff(mu(eta), eta)) = 0;

>Eqn3 := 2*U(eta)*(V(eta)+1)+(W(eta)+(1-n)*eta*U(eta)/(n+1))*(diff(V(eta), eta))-mu(eta)*(diff(V(eta), eta, eta))-(diff(V(eta), eta))*(diff(mu(eta), eta)) = 0;

>bcs1 := U(0) = 0, V(0) = 0, W(0) = 0;

>bcs2 := U(20) = 0, V(20) = -1;

>R1 := dsolve({Eqn1, Eqn2, Eqn3, bcs1, bcs2}, {U(eta), V(eta), W(eta)}, initmesh = 30000, output = listprocedure, numeric);

Error, (in dsolve/numeric/bvp) precision is insufficient for required absolute error, suggest increasing Digits to approximately 23 for this problem

>for l from 0 by 2 to 20 do R1(l) end do;
>plot1 := odeplot(R1, [eta, U(eta)], 0 .. 20, numpoints = 2000, color = red);

Error, (in plots/odeplot) input is not a valid dsolve/numeric solution

I have tried increasing the Digits as suggested to 23, 25, 30, 31 up untill 500 yet still same error occur suggesting to increase the Digits. Is there any other way to solve this kind of error? Can someone help me? Thank you in advance.

Hi. I want to solve a system of equations. But I got this type of error. 

>restart;

>Digits := 15;
>with(plots):n:=0.7:Pr=1: mu(eta):=(diff(U(eta),eta)^(2)+diff(V(eta),eta)^(2))^((n-1)/(2)):
>Eqn1 := 2*U(eta)+(1-n)*eta*(diff(U(eta), eta))/(n+1)+diff(W(eta), eta) = 0:
>Eqn2 := U(eta)^2-(V(eta)+1)^2+(W(eta)+(1-n)*eta*U(eta)/(n+1))*(diff(U(eta), eta))-mu(eta)*(diff(U(eta), eta, eta))-(diff(U(eta), eta))*(diff(mu(eta), eta)) = 0:
>Eqn3 := 2*U(eta)*(V(eta)+1)+(W(eta)+(1-n)*eta*U(eta)/(n+1))*(diff(V(eta), eta))-mu(eta)*(diff(V(eta), eta, eta))-(diff(V(eta), eta))*(diff(mu(eta), eta)) = 0:
>Eqn4 := (W(eta)+(1-n)*eta*U(eta)/(n+1))*(diff(theta(eta), eta))-(mu(eta)*(diff(theta(eta), eta, eta))+(diff(mu(eta), eta))*(diff(theta(eta), eta)))/Pr = 0:
>bcs1 := U(0) = 0, V(0) = 0, W(0) = 0, theta(0) = 1:
>bcs2 := U(20) = 0, V(20) = -1, theta(20) = 0:
>R1 := dsolve({Eqn1, Eqn2, Eqn3, Eqn4, bcs1, bcs2}, {U(eta), V(eta), W(eta), theta(eta)}, initmesh = 20000, output = listprocedure, numeric);

Error, (in dsolve/numeric/bvp/convertsys) too few boundary conditions: expected 8, got 7

>for l from 0 by 2 to 20 do R1(l) end do;
>plot1 := odeplot(R1, [eta, theta(eta)], 0 .. 20, numpoints = 2000, color = red);

What is the problem actually because based on the paper that I refer to, there is only 7 bc. 

Can anyone help me?

Thankyou in advance.

Hello

Is there any option for impoting MATLAB's variables eith struct format (*.mat)?

Could you please to help me!

Thank you.

Hi!

In Mathematica 10.0 were introduced regions with functions like TransformedRegion, ReginIntersection, etc. Moreover, it is easy to check if a point is inside a region, etc.

I would like to ask if in Maple I could use some API with similar functionality?. For instance, I would like to get integer points which lay inside an intersection of two cubes. How I could do this in Maple?

How to get the approximation of definite integral if explicit integral could not be found?

explicit_integral_could_not_be_found.mw

If explicit integral could not be found, is there any function or method to get the approximation of a definite integral?

how to answer of materix export to Excel.

restart;

Digits:=5;

f:=(x,y)->2*x*evalf(Int(sqrt(1+y^2*(t*x-1)^2/(1-(t*x-1)^2)), t = 0 .. 1)):

for i to 20 do

for j to 11 do

a[i,j]:=f(0.1*i, 0.1*(j-1));

od: od:

interface(rtablesize=infinity):

A:=Matrix(20,11, (i,j)->a[i,j]):

V:=<seq(i,i=0.1..2,0.1)>:

W:=Vector[row]([cat(x,` \\ `,y),seq(i,i=0..1,0.1)]):

<W, <V|A>>;

I want Positive values of Arcsin but maple give to me Negative values of Arcsin?

my function is f=arcsin(1-x), 0<x<2 and f>0. and f(2)=3 pi/2 but in maple f(2)=-pi/2.

I want positive values of f Without adding anything to f.

Thanks.

Of course it's easy to write a procedure to compute the ith Horner polynomial of a polynomial but I'm carious to know if there is any built-in command for doing this, I searched in help of Maple and found several ways but they convert or rewrite the input polynomial in Horner form so the output is last Horner polynomial which is equal to the input polynomial with this difference that it is written in a kind of factorization form which shows the Horner structure and ofcourse with looking at it you can read other Horner polynomials too but why not having exactly the ith Horner for the output? So is there any other command with output being the ith Horner?

I want Positive values of Arcsin but maple give to me Negative values of Arcsin?

arcsin(-1);
-pi/2

but I want Positive values of Arcsin Namely:

arcsin(-1)=3 pi/2

For the following Maple 2015 procedure and funtion call

 f := proc(x,y) local a; global b;
    if x < y then
        a := x; b := y + a;
    else
        a := y; b := x + a;
    end if;
    a + b + x + y
end proc:
stopat(f);
                              [f]
f(2, 3);
 

Maple help topic "The Maple Debugger" shows the following example:

 f:
    1*   if x < y then
           ...
         else
           ...
         end if;
 
 DBG> stopwhen b
 [b]
 f:
    1*   if x < y then
           ...
         else
           ...
         end if;
 
 DBG> cont
 b := 5
 f:
    6    a+b+x+y
 
 DBG> showstat
 f := proc(x, y)
 local a;
 global b;
    1*   if x < y then
    2      a := x;
    3      b := y+a
         else
    4      a := y;
    5      b := x+a
         end if;
    6 !  a+b+x+y
 end
 
 DBG> quit
 Warning, computation interrupted

However, when I run the procedure in Maple Notation (1D) the Interactive Maple Debugger pops up with syntax quite different from the example.  How can I turn the Interactive Debugger off and use commands such as DBG> stopwhen b in the command-line version?

Thanks!  Les

hi .how i can clarify expression in maple that in running dont asked me again..

for example attached file

2)how i can deleted one parameter of 
Memory in maple or
Restart it??

Hello, I'm trying to enumerate matrices, each P [j] with j = 1,2,3 ... n-1. , and also can also the value of its elements with P [j] (r, k) for example.
n:=4;

for j from 1 to n-1 do 
P[j]:=Matrix(n); 
for l from 1 to n do
P[j](l,l):=1;  
end do; 
end do;
Error, invalid operator parameter name

Regards.

Hello,

I try to get the first ten fractions of Pi with the commands "seq" and "nthconver".

I tried this:

a:= cfrac(Pi);
CFRAC([3, 7, 15, 1, 292, 1, 1, 1, 2, 1, 3, ...])
sec(nthconver(a,i),i=1..10);

But it doesn't work.

Who can help me?

It took me a while to figure out what was causing this unusual sort result;

I loaded the MTM package because I want to convert numbers to integers for indexing. This sort result seem like it could be a bug.

Download MTMsort.mw

f=2*x*(int(sqrt(1+y^2*(t*x-1)^2/(1-(t*x-1)^2)), t = 0 .. 1))    ,0<x<2,   0<y<1,

I want to Determine the value of f for the various values of x,y For a domain So that x , y Changing with steps 0.1. for example: