Dear people in Maple Primes,

I have a question about how to solve a system of equations.

In the following equation, I want to eliminate D(a).

x := D(a*b*c = 3*d); 
y := D(a^2*b^3*c = 3*a);

For this purpose,

a code of 

d_a := isolate(x, D(a));

eval(y, d_a);

works well. But, for me, this code is a little laborious.

Is there any better way than the above way?

Thanks in advance.

taro yamada

How to create a long progression in maple (up to 100 000 000 000), where a member is a previous one plus a certain number. For example: 25, 50, 75, 100... and then divide the whole series (all the members) by a number. What command should one use?

Hi all,

I try  to plot phase portrait the below DAEs, 

diff(S(t), t)=-β*(1+δ*sin2Πt)*S(t)*I(t)-μ*S(t)+μ,

diff(I(t), t)=β*(1+δ*sin2Πt)*S(t)*I(t)-γ*I(t)-μ*I(t),

0=S(t)+I(t)+R(t)-1.

where

μ=0.01,

β=1510,

δ=0.02,

γ=50,

I really appreciate your help.

a:=rand(0..8):
b:=rand(0..8):
c:=rand(0..8):
d:=rand(0..8):
e:=rand(0..8):
f:=rand(0..8):
a()+b()+c()+d()+e()+f()=8;

This is my  programming code.

I want ot set six random summation is  8. 

But the random summation can't reach 8.

Hi, 

  I would like to a string of characters to a file. For example,

***

str:="hello world";
WriteFile[APPEND]("D:\\output3.txt", str);

***

  It doesn't work. I did not get output3.txt :(  How should I do, to write a string of characters, such as "hello world" to a file?

Thank you

hi

please help me :

BC1 = diff(T(x, 0), y)=1000

BC2 = diff(T(x, 0.000025), y)=2000

IC = T(0,y)=0

where :

u(y)=-1.218493440*10^11*y^2+4.244913600*10^6*y+0.033

Download PDE_Sol.mw

qu.mw 

this is my code but there has smoe problom

i make the MathContainer0 and MathContainer1 can be entered number

 i plot the loop circle, and then i want to show te insection of two circle,that the center and radius of two 

 depends on the value of MathContainer0 and MathContainer1 that we entered

any one can help me? thx

I wrote a maple code and it returns: if statement error to me.

How can I fix it?

Regards

F1 := proc (rlist, deltalist) local sum1, i; sum1 := 0; for i to 8 do sum1 := sum1+rlist[i]*deltalist[i] end do; if `mod`(sum1, 24) = 0 then return true else return false end if end proc;

 F2 := proc (rlist, deltalist) local i, sum2; sum2 := 0; for i to 8 do if deltalist <> 0 then sum2 := sum2+40*rlist[i]/deltalist[i] end if end do; if `mod`(sum2, 24) = 0 then return true else return false end if end proc;

F3 := proc (rlist, deltalist) local product, i; product := 1; for i to 8 do product := product*deltalist[i]^rlist[i] end do; if ceil(sqrt(product)) = sqrt(product) then return true else return false end if end proc;

myProc40:=proc(deltalist) local r1, r2, r4, r5, r8, r10, r20, r40,rlist: for r1 from -1 to 3 do for r2 from -1 to 3 do for r4 from -1 to 3 do for r5 from -1 to 3 do for r8 from -1 to 3 do for r10 from -1 to 3 do for r20 from -1 to 3 do for r40 from -1 to 3 do rlist:=[r1,r2,r4,r5,r8,r10,r20,r40]: if (F1(rlist, deltalist) = true) then if(F2(rlist,deltalist)=true ) then if (F3(rlist, deltalist) = true) then if ((gcd(1,1)^(2)*r1)/(1)+(gcd(1,2)^(2)*r2)/(2)+(gcd(1,4)^(2)*r4)/(4)+(gcd(1,5)^(2)*r5)/(5)+(gcd(1,8)^(2)*r8)/(8)+(gcd(1,10)^(2)*r10)/(10)+(gcd(1,20)^(2)*r20)/(20)+(gcd(1,40)^(2)*r40)/(40)>0) and ((gcd(2,1)^(2)*r1)/(1)+(gcd(2,2)^(2)*r2)/(2)+(gcd(2,4)^(2)*r4)/(4)+(gcd(2,5)^(2)*r5)/(5)+(gcd(2,8)^(2)*r8)/(8)+(gcd(2,10)^(2)*r10)/(10)+(gcd(2,20)^(2)*r20)/(20)+(gcd(2,40)^(2)*r40)/(40)>0) and ((gcd(4,1)^(2)*r1)/(1)+(gcd(4,2)^(2)*r2)/(2)+(gcd(4,4)^(2)*r4)/(4)+(gcd(4,5)^(2)*r5)/(5)+(gcd(4,8)^(2)*r8)/(8)+(gcd(4,10)^(2)*r10)/(10)+(gcd(4,20)^(2)*r20)/(20)+(gcd(4,40)^(2)*r40)/(40)>0) and ((gcd(5,1)^(2)*r1)/(1)+(gcd(5,2)^(2)*r2)/(2)+(gcd(5,4)^(2)*r4)/(4)+(gcd(5,5)^(2)*r5)/(5)+(gcd(5,8)^(2)*r8)/(8)+(gcd(5,10)^(2)*r10)/(10)+(gcd(5,20)^(2)*r20)/(20)+(gcd(5,40)^(2)*r40)/(40)>0) and ((gcd(8,1)^(2)*r1)/(1)+(gcd(8,2)^(2)*r2)/(2)+(gcd(8,4)^(2)*r4)/(4)+(gcd(8,5)^(2)*r5)/(5)+(gcd(8,8)^(2)*r8)/(8)+(gcd(8,10)^(2)*r10)/(10)+(gcd(8,20)^(2)*r20)/(20)+(gcd(8,40)^(2)*r40)/(40)>0) and ((gcd(10,1)^(2)*r1)/(1)+(gcd(10,2)^(2)*r2)/(2)+(gcd(10,4)^(2)*r4)/(4)+(gcd(10,5)^(2)*r5)/(5)+(gcd(10,8)^(2)*r8)/(8)+(gcd(10,10)^(2)*r10)/(10)+(gcd(10,20)^(2)*r20)/(20)+(gcd(10,40)^(2)*r40)/(40)>0) and ((gcd(20,1)^(2)*r1)/(1)+(gcd(20,2)^(2)*r2)/(2)+(gcd(20,4)^(2)*r4)/(4)+(gcd(20,5)^(2)*r5)/(5)+(gcd(20,8)^(2)*r8)/(8)+(gcd(20,10)^(2)*r10)/(10)+(gcd(20,20)^(2)*r20)/(20)+(gcd(20,40)^(2)*r40)/(40)>0) and ((gcd(40,1)^(2)*r1)/(1)+(gcd(40,2)^(2)*r2)/(2)+(gcd(40,4)^(2)*r4)/(4)+(gcd(40,5)^(2)*r5)/(5)+(gcd(40,8)^(2)*r8)/(8)+(gcd(40,10)^(2)*r10)/(10)+(gcd(40,20)^(2)*r20)/(20)+(gcd(40,40)^(2)*r40)/(40)>0 ) then (print(`f(q) is in Sk with the following r values`,rlist)) end if: end if: end if: end if: end do: end do: end do: end do: end do: end do: end do: end do: end proc;

How can I find interesting Math apps written by Maple ?

Good morning.

I am working on engineering drawing project. I request your kind suggestions for

the above cited subject.

With thanks & Regards

M.Anand

Assistant Professor in Mathematics

SR International Institute of Technology,

Hyderabad, Andhra Pradesh, INDIA.

Dear all,

I tried to use pdsolve to solve the parabolic pde but get the unexpected answer:

Is it the PDESolStruc or the other structure? Where can I find the description about this kind of structure.

Thanks.

Say I have

a.mpl

b.mpl

c.mpl

each of them can be ran seperately. While I am running a single file, it looks like that the machine is not "using" too much computation power. I wonder if it's possible to run multiple at the same time ?

My CPU is i7 940X, with 4 dual core processors, so it has 8 threads.

I know that the GUI can run multiple worksheets seperately, but if in one of the worksheet, i click "run all" (!!! botton),  I will have to run each line separtely by clicking one at a time.

Is there a better way to do this? What's the best way to do this? I hope to somehow 'maximize' the full use of my CPU (without changing the code).

casper

Is this a  false positive, where Maple is solving an ODE which is supposed to be unsolvable?

Accoding to http://www.maplesoft.com/compare/mathematica_analysis/Comparison_Maple_Mathmatica_DEs_Kamke.pdf and considering ODE 13

Maple 18.01 does give an answer for the above ODE. I verfied the ODE from the book as well. The answer returned by Maple is very large, but it does solve it in 195 CPU seconds. Therefore the question is: Is this a false result? Or is the above document have an error in it and ODE 13 is actually solvable?

restart;
ode:=diff(y(x), x$2)-(a*y(x)^2+b*x*y(x)+c*x^2+alpha*y(x)+beta*x+gamma)^(-3/2);
sol:=dsolve(ode,y(x)) assuming a::NonZero; #I get an answer with or without this assumption. The book has the assumption
odetest(sol,ode);

btw,

 odetest(sol,ode)

gives an error as well. May be this is related to the issue or not. Not sure now.

Hi:

when use the dsolve,numeric,I see error,why?

f := (x, t) -> piecewise(t < 10, 0.480e9*(1-(1/10)*t)*sin(Pi*x), 10 < t, 0)

eq1 := diff(y(t), t, t)-y(t)^2-f(x,t) = 0:
eq2 :=simplify( int(lhs(eq1)*sin(Pi*x), x = 0 .. 1) = 0):

dsolve({eq2, y(0) = 0, (D(y))(0) = 0}, numeric)

initial conditions are zero.

Hi,

  I have a loop code, such as

****

i_max:=10;

for i from 1 to i_max do
  blah blah blah

end do;

****

  I would like to clean memory, something like restart suppose to do, after each cycle. Restart could only work at top level. How should I do to clean memory after each cycle?