# Items tagged with equationequation Tagged Items Feed

### 6 equations , 6 unknowns?...

January 06 2014
0 1

I am trying to solve a set of equations for a Fluid dynamics problem and I cannot get a result...Any ideas why?

rho := 1.184;
nu := 1.562*10^(-5);
ID := .15;
L := 24.5;
Kl := 12.69;
Ho := 50.52;
a := 2.1*10^(-5);
E := 0.1e-2; alpha := 1.05;

sys := {Re = ID*V/nu, hl = (f*L/ID+Kl)*V^2/(2*9.81), Vflow = (1/4)*Pi*ID^2*V, Hrequired = alpha*V^2/(2*9.81)+hl, Hrequired = -a*Vflow^2+Ho, 1/sqrt(f) = -1.8*log[10](6.9/Re+(E/(3.7))^1.11)};

solve(sys*{Re, V, f, hl, Vflow, Hrequired});
%;
Error, (in unknown) invalid input: Utilities:-SetEquations expects its 2nd argument, equations, to be of type set({boolean, algebraic, relation}), but received {{Re = (9603072983/1000000)*V, hl = (5096839959/100000000000)*((1633333333/10000000)*f+1269/100)*V^2, Vflow = (9/1600)*Pi*V, Hrequired = (5351681957/100000000000)*V^2+hl, Hrequired = -(21/1000000)*Vflow^2+1263/25, 1/f^(1/2) = -(9/5)*ln((69/10)/Re+27367561/250000000000)/ln(10)}}

### mapping a function to an equation...

January 04 2014
0 16

Hello

I calculated following two expressions, x1,and x2.

x1:=map(f,a+b);

x2:=map(f,y=a+b);

The results of these are

f(a) + f(b)

f(y) = f(a + b)

for each. And, I can understand the logic of this.

If I want to derive the result of x2 as f(y)=f(a)+f(b), how should I do about x2?

Isn't there other way than to write

map(f, lhs(x2))=map(f,rhs(x2))

?

Taro

### How to solve nonlinear equation numerically in Map...

December 20 2013
1 3

restart;

diffeq := diff(w(r), $(r, 1))+2*beta*(diff(w(r), $(r, 1)))^3-(1/2)*S*(r-m^2/r) = 0;

con := w(1) = 1;

ODE := {con, diffeq};

sol := dsolve(ODE, w(r), type = numeric);

How can i have numerical solution of the above differential equation with corresponding boundary condition?

December 14 2013
1 1

### System of differential equations and algebraic equ...

December 14 2013
0 1

Hello, how can i solve these equations

eq[1]:=a'[1](t)*p[1](x)+b*a[1](t)*p[1](x)

eq[2]:=a'[2](t)*p[2](x)+b*a[2](t)*p[2](x)

eq[3]:=a'[3](t)*p[3](x)+b*a[3](t)*p[3](x)

eq[4]:=c[1]*a[1](t)+c[2]a[2](t)+c[3]a[3](t)-q(t)

eq[5]:=d[1]*a[1](t)+d[2]a[2](t)+d[3]a[3](t)-p(t),

where p[i](x) , c[i] , d[i] , q(t) and p(t) are known functions?

### simplifying fraction of equations...

December 10 2013
0 5

I have to questions. One is the main one, about simplifying fractions.

This is equations.

jj:=L*theta*gamma[2]^2*(-1+alpha)/(delta[2]*(-alpha*gamma[1]^(-2*sigma+2)*gamma[2]^(2*sigma)-gamma[2]^2+gamma[2]^2*alpha));

kk:=expand(denom(jj)/gamma[2]^2);

ll:=op(1,kk);

mm:=simplify(ll,power);

nn:=mm-delta[2]+delta[2]*alpha;

oo:=numer(jj)/gamma[2]^2/nn;

pp:=(numer(jj)/gamma[2]^2)/(denom(jj)/gamma[2]^2);

From now, I will explain. Though as I don't know how to put a maple screen on this board I think I will have you feel some inconvenience, please forgive it.

I want to make jj more simple, dividing both of numerator and denominator of jj, with gamma[2]^2.

But, what I could at best was this. First, taking denominator of jj and deviding it with gamma[2]^2 and expanding it like kk. Second, as the first term among that expression had terms of gamma[2] on both of the numer and denom, I picked out the first term as ll in the above maple commands, and simplified it with option: power, in mm. Thirdly, I rewrote kk as in nn.

and Forthly, I rewrote jj with modification of deviding numerator and denominator with gamma[2]^2, using the result which I could get as I wrote above. oo is that. And the result of oo is what I wanted to get.

But, on the other hand, when i divided denom and numer of jj directly by gamma[2]^2, the result I can get then is not

good one: the output of pp is not what I wanted to get.

Is there more simple way to do what I did in the above? This is a first question.

And, another is how I can post the screen of maple on this question board?

I hope you will answer my question. I thank all of you who will answer these question in advance.

### how to do not to have maple simplify what I wrote....

December 10 2013
1 2

Dear people being here,

I have a question.

When I wrote as

aa:=(delta[1]*n[1])/(n[f1]*delta[1]);

maple returned as

aa := n[1]/n[f1]

How can I have maple express the original one, aa:=(delta[1]*n[1])/(n[f1]*delta[1]), not what returned to me?

I hope you will answer to my question.

taro

### simultaneous equations exp...

December 09 2013
1 8

I'm asked to solve the equations below simultaneously using fsolve.

f := x*exp((1 - x)*a);
f[2] := subs(x=f,f);
eq[1] := f[2] - x;
eq[2] := diff(f[2],x) + 1;

fsolve({eq[1],eq[2]},{x,a}):

fsolve doesn't seem to work here for some reason.

Any help help would be great!

Thanks

### solving equations ...

December 08 2013
1 5

Hi, i was wondering how you would solve the equation

30+1144*r^4-832*r^2=0,

exactly in maple.

Using the command

fsolve(30+1144*r^4-832*r^2);

-0.8301954535, -0.1950595709, 0.1950595709, 0.8301954535

Also, if possible how would you get maple to find the two exact positive solutions.

Thanks

### How do I format the following dsolve function from...

December 05 2013
1 2

The differential equation I'm solving for is:

### Solution to this Differential equation....

December 05 2013
1 3

I have a problem in excuting this differential equation in maple it takes a long time but yet no result.

> restart;

> Delta:= epsilon[2]-epsilon[1];

> epsilon[y] := epsilon[2]-(1/4)*Delta*(1-tanh(a*y))^2;

> z:= tanh(a*y) ;

> ODE[4]:= diff(Y(y),y,y)- ( a/2* Delta *(1-z)*(z^2-1))/(epsilon[2]- Delta*(1-z)/4)* diff(Y(y),y)-( beta^2+ mu[0]*epsilon[y]*omega^2)*Y(y) = 0;

> dsolve(ODE[4],Y(y));

does this always occur or i do have problem with my version of maple 15, 7 and 16.

### How do I see the workings of a equation?...

November 17 2013
0 3

I am just getting started with Maple and would like to know the following:

When I input an equation, for example (3.4)^2x+3 = 8.5, right click and select “solve for x”, the software gives me a value x=0.6256295444, although this is the final answer I require I also want to see how we arrived at that answer, I bought the software to use as a learning tool so I really need to be guided through the whole process.

Hope you can help.

### Maple runs solving variables in equation forever...

November 16 2013
0 5

Maple syntax for solving for t:

solve(14.2857*exp(-t)-0.0045exp(-1.0175*t)-14.2857*exp(-(t-5))-0.0045exp(-1.0175*(t-5))+7.368=0, t);

Note: Equation was obtained from chemical engineering process control problem. This is the case for t > 5. For t < 5, we have:

solve(-0.2457+14.2857*exp(-t)-0.0045exp(-1.0175*t)+7.368=0, t);

I have tried multiple times for both cases, but Maple still runs forever. How can I solve this issue?

### how maple can recognize numeric from symbol?...

November 09 2013
0 3

i have 3 equations which contains both numeric and symbols, how can i seprrate these to ?
for example :

> restart:
> eq1:=a[1]^3+a[2]+a[3]^2+50;

> eq2:=a[1]^2+5*a[2]+a[3]+44;

> eq3:=a[1]+a[2]+a[3]^2+74;

i want maple to seprate these three equations in two vectors,first vector including symbols and second one includes numerics , like this :
V1:=<<a[1]^3+a[2]+a[3]^2>,<a[1]^2+5*a[2]+a[3]>,<a[1]+a[2]+a[3]^2>>;

V2:=<<50>,<44>,<74>>;

eq:=<<eq1>,<eq2>,<eq3>>;

so that

is(V1+V2=eq);