## Problem with isolve...

Hello everyone,

I have some problems with the "isolve" command on Maple. I am trying to solve for integer a very easy system of equations. When I type the commands

restart;

n := 2;
isolve({sum(a[k], k = 1 .. n)-1 = 1}, d)

I get the expected {a[1] = 2-d, a[2] = d}. However, if I add conditions a[1],a[2] >= 0, that is the commands

restart;
n := 2;
isolve({ge(a[1], 0), ge(a[2], 0), sum(a[k], k = 1 .. n)-1 = 1}, d)

I get the warning "Warning, solutions may have been lost". What am I doing wrong? Is there a way to get Maple to give me the possible values?

David

## Derivative of functions with constants...

Hi everyone. Please excuse me in advance, as I am new on this website and to Maple.

So I am using Maple 16 and I want it to give me the derivative of a function that has constants in it, for example f(x)=(x-a)(x-b). I wrote the (probably stupid) commands on Maple:

> f(x):=(x-a)(x-b);

> diff(f(x), x);

but the result is not the expected (2x-a-b), but rather (D(x))(x-b)-(D(a))(x-b). What would be the right things to write to get what I need?

David

## How to map a piecewise?...

Hello,

I use a map() command to get the values of function for each element of vector. Here is an example of a simple task:

restart:

A:=[1,2,8];

f1:=x->2*x;
f1_table_A:=Vector([map(f1,A)]);

I would like to do the same with piecewise function but it doesn't work. Here is an example:

restart:
with(plots):
f:=2*x:
g:=x^2:

h:=x->piecewise( 0<=x and x<= 5, f, 5<x and x <= 10, g ) ;
A:=[1,2,8]:
h_table_A:=map(h,A):

Is it possible to work with piecewise function? Maybe someone has an idea how to do it in different way?

Kind regards,

Iza

## Problem with solving equation...

Hallo,

I am rather a beginner in Maple, so I will be grateful for understanding.

I try to solve the equation with one unknown. To create this equation I firstly had to solve the set of four equations so it is very complicated. Maple is able to create the plot of it but command fsolve is not sufficient to solve it. Here is my procedure:

restart:
z1:=H/mg*cosh(mg/H*(x+C11))-C21:
z2:=H/mg*cosh(mg/H*(x+C12))-C22:
tg_alpha1:=diff(z1,x):
tg_alpha2:=diff(z2,x):
r1:=H*subs(x=xP,tg_alpha2)-H*subs(x=xP,tg_alpha1)-P:
r2:=subs(x=0,z1):
r3:=subs(x=l,z2)-h:
r4:=subs(x=xP,z1)-subs(x=xP,z2):
mg:=2:l:=20:h:=5:xP:=l/5:P:=10:
C := solve({r1, r2, r3, r4}, {C11, C12, C21, C22}):
s1 := int(sqrt(1+(diff(subs(C, z1), x))^2), x):
s2 := int(sqrt(1+(diff(subs(C, z2), x))^2), x):
s := subs(x = xP, s1)-subs(x = 0, s1)+s2-subs(x = xP, s2):
eq1 := l0-subs(x = l, s):
l0 := 40:
plot(eq1, H=10 .. 11, colour = red);
H := fsolve(eq1 = 0, H = 10.7 .. 10.8);

I would be grateful for any help and indicating my mistakes.

Thanks

Iza

## Re-Installing Maple 16...

Hi all,

I'm going to call support tomorrow morning, but I figured I'd ask around here in the meantime. Thanks!

## ScatterPlot with Regression Line...

I imported data into maple from excel.  I was able to make a scatterplot with my data and a regression line, but I have been unsuccessful in trying to combine them both onto the same plot.  I tried multiple different ways but still could not get it to work.

I think it has to do something with the brackets around each element inside my imported array, but I am not sure.  Any ideas would be nice.

My objective is to put the regression line and scatterplot on same graph.project1.mwproject1.mw

Thanks much.

Matt

## Solving a big system of inequalities ...

Hello,

I have a problem with MAPLE. I would like to solve a system of 18 inequalities with 4 variables. The variables shall be rational numbers. I should also mention that I am not sure if the system has a solution. Here is my MAPLE code:

LinearMultivariateSystem({0 < (1/20)*b11, 0 < (1/20)*b1818, 0 < (1/20)*b22, 0 < (1/20)*b33, 0 < -653385574770525739/313841848320000+(1001/20)*b33+(3003/5)*b22+4004*b11-(91/5)*b1818, 0 < -476383516463665673/69742632960000+(3003/20)*b33-(1001/10)*b1818+(27027/2)*b11+(3861/2)*b22, 0 < -372810037848242383/52306974720000+(72072/5)*b11+(3003/20)*b33-(858/5)*b1818+2002*b22, 0 < -302968656462848461/125536739328000+(1001/20)*b33-(1001/10)*b1818+5005*b11+(1365/2)*b22, 0 < -94060277895192911/627683696640000+(91/20)*b33+273*b11-(7/10)*b1818+(91/2)*b22, 0 < -3219528868317343/14944849920000+468*b11+(91/20)*b33-(91/5)*b1818+63*b22, 0 < -1167616840098623/627683696640000+(7/10)*b22+(1/20)*b33+(21/4)*b11-(7/10)*b1818, 0 < 6620337745005653/9510359040000+(91/20)*b1818-(91/5)*b33-(6552/5)*b11-(819/4)*b22, 0 < 10321214321183681/627683696640000-(21/4)*b22-(7/10)*b33-28*b11+(1/20)*b1818, 0 < 19939504442621873/627683696640000-(7/10)*b33-(39/4)*b22-(364/5)*b11+(91/20)*b1818, 0 < 21128314477665001/24141680640000-(91/5)*b33-1848*b11+(1001/20)*b1818-(1001/4)*b22, 0 < 30458564958023749/6340239360000-(1001/10)*b33+(3003/20)*b1818-9828*b11-(27027/20)*b22, 0 < 78768022311702133/17933819904000-(1001/10)*b33-8580*b11+(1001/20)*b1818-(5005/4)*b22, 0 < 418747163878248241/52306974720000-(858/5)*b33+(3003/20)*b1818-16016*b11-(9009/4)*b22}, [b11, b22, b33, b1818])

I am sorry for the writing style but I do not know how to write the command in MAPLE-style in this forum:-)

The first 4 inequalities shall ensure that all four variables b11, b22, b33, b1818 are positive. When entering the command i get the following error:

Best regards,

Lucas

## solving quartic equation...

k^4-k^2*(4*u*m+2*q^2)+k*(8*m*E*q)+4*m^2*(D^2-e^2+(q^2/2*m-u)^2)=0

## Function defined as integral in ODE...

I have a function defined as an integral that can be computed numerically at every point, and MAPLE does it. When I use this function inside an ODE for another function, maple complains that unknown parameters must be initialized. It sees the integration variable in my definition of the function defined as an integral as a parameter. Is there a work around?

Attached you will find an worksheet with my example. The function defined as an integral is called YFD(x) and the independent function I am trying to evaluate numerically using dsolve is Y(x).

 (1)

## The function  that is defined as an integral and will enter the ODE

 (2)

 (3)

 (4)

 (5)

Attempt to solve ODE:

 (6)

 (7)

## Introductory Computer Science Final Exam...

Hello,

I need to prepare for a final exam for a introdutory computer science course in Maple.
My professor gives us mutliple choice questions, short answer questions and wiritng some codes.

what is the most efficient way to study for my final exam? or how should i study for an computer science exam. I am not really use to preparing for such a course.

Are there any websites that i can practice multiple choice questions?

Thank you very much.

## How do i graph parametric equations in 3d...

i have 3 equations that i need help graphing, i have tried but do not know much about maple.

the equations are x= sin u [7+cos((u/3)-2v)+2cos((u/3)+v)], y=cos u [7+cos((u/3)-2v)+2cos((u/3)+v)],

and z=sin((u/3)-2v)+2sin((u/3)+v) the limits are u from -pi to pi, and v is also from -pi to pi. please help

## error appear in maple ...

@Carl Love Dear Sir i am trying to solve the system of nonlinear ODE equation with semiinfinite domain by using shooting method . but i am receiving following error

"Error, (in isolate) cannot isolate for a function when it appears with different arguments"

how can i remove this error. i am unable to find the mistake. kindly help me

## Error trying to Solve unknown variable within a de...

Hi there,

I am trying to compute the following, and I am getting this error.

> A := map(convert, M, unit_free)*Unit('m'*(1/'s'^2));
(I had to put the Unit('m'*(1/'s'^2)) because the original units were kNm/s^2 (kg), and even though I simplified it, it's still using kNm/s^2, and leaves the m/s^2 for some reason when I try to remove the units. I tried simply changing the units on the original matrix, but the units menu has disappeared from the right-click menu!!)

> B := map(convert, K, unit_free);

solve;

Error, (in assuming) when calling 'Engine:-Dispatch'. Received: 'should not happen: Rename expects the input to contain unknown functions'

Why is it giving me this error? omega is an unknown variable that I am trying to solve for. I am going a modal analysis, so maybe there is a better way to find omega?

Any help appreciated!

Raquel