restart:assume(M>0);

Eq1 := diff(psi(y), y, y, y, y)-M*(diff(psi(y), y, y))-Gr*b*y = 0;

bcs1:=psi(0)=0,(D@@2)(psi)(0)=0,psi(h)=-F/2,D(psi)(h)=A;

res1:=(dsolve(Eq1));

res2:=(dsolve({Eq1,bcs1},psi(y)));

match(rhs(res2)=rhs(res1),y,s);

s:

C3:=eval(_C3, s);

I am unable to find the constants. Anyway around this?

i am solving 4 ODE with boundary condition..

> restart;
> with*plots;

then i got this error..

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

i dont know where i need to change.. could you help me..

Hello, I'm new here, I hope there is someone willing to give me a hand with my problem. I've been trying to solve a problem with a for loop and I have errors in my code, could you please tell me what's wrong with the  bold part?

restart;

with(plots);

g := proc (F, A, B, X0, g::evaln) local f, a, b, E, x0, erreur, N, n, x1, ps, pp, pic; f := F; a := A; b := B; x0 := X0; E :=

evalf(abs(f(x0)));

erreur := 0.1e-3;

N := 100;

n := 0;

for i to N do x1 := evalf(x0-f(x0)/(D(f))(x0));

E := abs(f(x1));

n := n+1; ps[n] := plot([[x0, 0.], [x0, f(x0)], [x1, 0.]], color = green, thickness = 2);

x0 := x1 end do; g := evalf(x1); pp := plot(f(x), x = a .. b, color = red); pic := seq(ps[i], i = 1 .. n); display(pp, pic) end proc;
Warning, `i` is implicitly declared local to procedure `g`
f := proc (x) options operator, arrow; sin(x)-cos(2*x)+.2 end proc;
x -> sin(x) - cos(2 x) + 0.2
a := 0; b := 6;

Thank you very much!

What is the weak solution integral equation for 

d² u(x)/dx² -(1+x² ) u(x)-1=0

This is better explained with simple example. Suppose I have these 2 equations

a:='a';b:='b';x:='x';
eqs:=[3*a+4*b = 3*x, 5*a+7*b = 7*x];

What I want is to solve for (a/x) and (b/x) from the above, and not for "a" and "b".

Currently, I do this manually as follows. First divide both equations by 'x' to obtain the ratio. I had to do this manually as writing eqs/x gave expression which was hard to work with for what I want to do. I could not simplify it for what I wanted. So I typed this

eqs2:=[3*(a/x)+4*(b/x)=3,5*(a/x)+7*(b/x)=7];   %manually typed !

Now used algsubs to replace (a/x) by new variable z1, and replace (b/x) by new variable z2, then solve for z1,z2 (btw, I had to do algsubs one at a time. (need to look at this later, but not impotant)

algsubs(a/x=z1,eqs2);
algsubs(b/x=z2,%);
solve(%,{z1,z2});

       {z1=-7,z2=6}

Is there a way or function(s) to automate this. The hard part is telling Maple to use the ratio as new variable starting from set of equations.

Hy i need your help experts,

I have à small program for some variables calculations and im intrested to plot loop result,

Here is the program:

I just want to assign the results of my loop to a matrix to be easily ploted.

Thak you for help.

Dear all;

Please how can I plot the error between the two function.

Hi:

can I use Laplace Transform Method for solve Nonlinear ODE in maple?

This has been buggin me all day, but if i define a variable with an expresion say "a:=3 x+5" and i then want to assign this expression to a function like so "f:=x->a". if i then call f(7), maple return with "3 x+5" so just returning the value of a without substituting x with 7.

Is there any way in which i can define a function this way?

Hello everybody,

Since I am geting older, I need to fix the font size form 12 to 14.  I have been tryong to find where to do that permanent change.  But without success.  Could someone help to to resolve this problem.  Thank you in advance for your help.

--------------------------------------
Mario Lemelin

Maple 18 Ubuntu 13.10 - 64 bits
Maple 18 Win 7 -  64 bits
messagerie : mario.lemelin@cgocable.ca
téléphone :  (819) 376-0987

I have a function. It's calculating coefficients of a polynomial.

So when it's done, I have the variables a0, a1, a2,a3 ... aN

where N is an input value and could be any positive integer.

Now, I just want to show them on the screen. So if I have, say , a0=1.3 and a1=5.76, I want this to appear:

1.3x + 5.76x²

That's all. I just want a loop that does this:

for term from 1 to N do:

    print( a0 ); print (x^N); print ("+");

od:

so all the terms come out on the same line, as in my example above. I've tried so many ways, but each time it ignores the numerical values of a0 and just writes "a0" on the screen, or breaks it up into a set, or puts || marks everywhere, or does it on sequential lines, or something or something or something.

I have Maple 16 for Windows 64-bit. How to get a printable Maple 16 Quick Reference Card? Also, how to save the Maple 16 Quick Reference Card as a separate file? (When I try to copy the Card I get en error message "selection too large").

How can I use separation of variable to solve heat equation u_t=u_{xx on a rod of length pi/4 with u(0,t)=0, u(pi/4)=0 and u(x,0)=x(pi/4-x)} 

then solve heat equation by laplace transform

Dear Maple experts,

I would like to generate population data that is the best possible approximation of a multivariate normal distribution with a specified covariance matrix and vector of means. I do not want to draw a sample from a multivariate distribution, but I want the population values itself which are approximately multivariate normal distributed. The size of the datamatrix should be limited, otherwise I could draw a huge sample from a multivariate normal distribution. For instance, I would like to generate a 200 by 6 data matrix that is the best (or at least good enough) approximation of a MVN distribution. For a bivariate normal distribution one could calculate the probalities of a grid by integrating the density, but for six variables that seems undoable. 

Before trying the invent the wheel again, I think I will ask this question to experts, because it is unlikely that there is no already existing algorithm that does the job pretty well.

Thanks in advance,

Harry Garst

i have a list of data, i can plot them with point plot,but i can not plot it in line style not point, could anyone help ? tnx for your help.