MaplePrimes Questions

Search Questions:

Latest Questions Latest Questions Feed

hello guys,

 

i have 4 differential equations with 4 unknown functions and i want to find functions , what is your idea ?

 

diff.mw

 

thank you very much

Hello, Currently when I calculate something, for example R=U/A where R is resistance, U is voltage and A is current, I get the answer in Volt/Ampere in stead of ohm. How do I change that?

Then, if the result is something like 3.124*10^-4 , how do I make maple output this in an engineering way, this would be 10^3, 10^6, 10^9 etc. to begin with?

Sorry if I formulate this wrongly, English is not my first language and I could not find an answer to this after some research.

Thank you

 

UPDATE and solution: for future reference:

You don't need to type out the whole unit like this:

1.0*Unit(volt)/(2000.0*Unit(ampere));

in stead you can do this:

(1.0*V)/(2000.0*A);

I got the V and A from the SI Units palette on the left hand side,

 ---

To answer my own question about the engineering notation, this can be "forced" by clicking on "Format" -> "Numeric Formating..." -> Engineering and then choosing the number of decimals. apply and set as default. After you are going to have to copy and recalculate your math as the !!! wont do it.

hi guys, i have a complicated 4 set equations and i want to solve it,

one way is to find a solution for an equation and check it manually in other equations but i am looking for better method

eqq.mw

 

thanks

Hello. My question is in the attached file.

Question.mw

I have a linear problem with 4 variables (p0, p1,p2, p3) and a list of inequality constraints (shown below).  I would like to plot a polyhedral in 3 dimensions (p1,p2, p3 and omitting p0) showing the region that satisfies the inequalities.  That is, something similar to plots[inequal] but in 3d.  Any pointers would be appreciated.

/* Constraints */
+p0 <= 60;
-p0 +p1 >= 4;
-p0 +p2 >= 5;
-p0 +p3 >= -12;
+p0 -p2 >= -33;
+p1 -p2 >= -36;
+p2 <= 67;
-p2 +p3 >= -35;
+p0 -p3 >= 2;
+p1 -p3 >= 0;
+p2 -p3 >= 11;
+p3 <= 57;
+p0 -p1 >= -7;
+p1 <= 43;
-p1 +p2 >= 0;
-p1 +p3 >= -9;

 

in Maple of a function with respect to a vector that contains product of variables?

I appologize before hand from my abuse of notation. 

Suppose I have a function

f:= x*y*z + 3*x^2*y*z;

and a vector defined as 

v:= <x*z | x^2*z>; #Column vector

and I would like to comput df/dv

So that the result from the Jacobian would be

J=<y , 3*y>; #Row vector

This is a simple example that can be solved by looking, but I would like to know if there is a way in maple to solve something like this. Some of the problems that I find are
1) The variables x*y*z commute i.e. x*y*z=z*x*y=y*z*x=x*z*y
2) And if I apply partial derivatives like  df/(dx*dz) = y+6*x*y and df/(dx*dx*dz) = 6 which is not the result that I desire, because what I want is the partial derivatives with respect to the functions x*z and x^2*z not to the variables x and z.

My application is far bigger than this example that I am posting, this is why I would like to find a way to produce this type of Jacobian. Any suggestion will be highly appreciate it.

for polynomials,

nops(10*x^2)

it return 2, but it is not 1

would like to count some differential equations' terms

for example

b(t)*da(t)/dt + a(t)*b(t) , number of terms is 2

Hello people in mapleprimes,

I have a question.

f1:=1+x:

unapply(f1,x);

returns x->1+x , with maple realizing 1+x is assigned to f1.

But, its short form

x-> f1;

returns

x->f1;

Why does this occur, and how can I have maple return the former result with x->f1 being input?

Thank you in advance for your help.

taro

 

Hi fellow Maple users,

I'm trying to solve an eigenvalue problem of Ax=wx, where A is a 6 by 6 Hermitian matrix with two parameters x and y. I want to solve it for w and then plot3d it with x and y as unknowns. The way I have been doing is first find the characteristic equation Determinant(A-wI)=0 and then solve it for w, and then plot3d the solutions within a range for x and y. My problem is sometimes solve(Determinant(A-wI)=0,w) would give me the 6 solutions expressed in x and y, but sometimes when the numbers in A are changed it will only give me a Rootof solution with which I cannot plot. I'm wondering if there is a better way to do this. I'm actually not very interested in the symbolic solution of w expressed in x and y, just the plot, so if there is a numerical alternative it's good too.

Thank you in advance!

I have a maple proc for which I would like to find parameters to fit data I have. The proc has an 'if' statement in it, and when I try to use the CurveFitting function 'NonlinearFit' function, I'm getting an error.

Is there a curve fitting function that can be used with procs with 'if' statements in them?

Thanks. 

restart:

f:=exp(-I*Im(s)*(t)); # I is iota, s is a complex number and t is time.

simplify(%);

Thanks

hi

I want help. 

my question is if I have coupled system of x and y variable . how can I find polynomial between these system?

Is there any simple way to extract the feasible range for the variables from solve result ?

For example, when I do solve({x-y = 10, x+y < 100}) I get {x = y + 10, y < 45}

From here, I need -inf<y<45 and -inf<x<55. Is it possible ? (I tried few methods, but it is not working for all cases.)

Why am I getting different results in these two cases ?

 

Hello maple prime users

I have used the sequence command and series command in Maple before, but seem to have hit a little hurdle with a particular problem.

I want to run the expression:

h(a,b,c):=b!*(a+c)!*sum(F,n=0..c)

   Where F:=(-1)^n*binomial(c,n)*N(a+n):

   Where N(a):=(-1)^n*[evalf(ln(2)) - 1 + 0.5 -1/3 + 1/4 +... + (-1)^a/a]:

I ran a test case using the following code:

restart:
a:=1:
b:=2:
c:=3:
tot:=0:
F:=((-1)^(a+n)/(a+n)):

for n from 0 to c do
      Seq_F2:=(-1)^(a+n):
   
      Seq:=[seq(F,n=0..n)];
      Seq2:=convert(Seq, `+`);

      final:=Seq_F2*(evalf(ln(2))+Seq2);

      SS:=(-1)^n*binomial(c,n)*final;

      S:=(b!*(a+c)!)*SS;
      tot:=tot+S;
od:
tot;

This works for the case where a =1, but will not work for a>1 as in the N(a+n) sequence it misses out the terms in the series for a-1, a-2 etc.... So when a = 2 it misses out the -1 of the sequence and when a = 3 it misses out the -1 and 1/2. Are there any tips on how to overcome this?

 

Best regards

 

- Yeti

1 2 3 4 5 6 7 Last Page 3 of 1194