## Volume of Revolution...

Hi guys,

I'm having trouble trying to get this feature to work.  I've defined a function, however, when I try to get execute a VolumeofRevolution command, all I get is the repeated command written in blue. ..

I've attached the worksheet.

Thanks for any help!

## How to plot trajectory using pointplot?...

Hi there,

I got two ordered lists of data (X and Y coordinates of body).

How I can plot a trajectory Y vs. X via pointplot?

## Equation...

> y1 := x-> piecewise(0<=x<=c, m1*x+b1, c<x<=1, m2*x+b2);

Error, unexpected relational operator

I don't know why it gives me this error, I underline where the cursor goes. Can anyone tell me what is my error?

Thanks

## How do I get the available memory with a maple com...

Hi,

I want to know how much memory Maple "sees" as available on command line execution. How can I get the information that appears on the classic worksheet as "Bytes" and "Available" with a Maple command?

Thanks

## type,property: what has changed?...

Short question: why does > type(Not(x::posint),property); show 'true' in Maple 10 (and below), and 'false' in Maple 11? What has changed? -- Regards, Franky

## Command solve in Maple 9.5 and Maple 11...

Dear all,

first I use Maple 9.5:

solve(x^3-8*x^2+12*x-4,x);

gives back 3 complex roots - in this moment I again know, it isn't bug.

Then I use Maple 11 with the same result.

Next test in Maple 11:

with(RealDomain): solve(x^3-8*x^2+12*x-4,x);

gives back only 2 real roots! Way?

Thanks.  Jan

## how to solve an ode numerically?...

hey guys.. i have put input this in maple.. but it doesn't seem to solve it..

ode:= D(D(y(t)))- u*(1-(y(t)^2))*D(y(t)) + y(t)=0;
ics:=y(0)=0.2, D(y)(0)=0;
y(0) = 0.2, D(y)(0) = 0
dsolve({ode,ics},numeric);

Error, (in unknown) invalid input: op expects 1 or 2 arguments, but received 0

## Percentage points of the F-distribution...

The F-distribution (also known as Snedecor's F distribution or the Fisher-Snedecor distribution) depends on two separate degrees of freedom, m and n. It is defined by (Eq. 2 in MathWorld):

In Maple notation:

> fdist:=(x,m,n)->GAMMA((m+n)/2)*(m/n)^(m/2)/GAMMA(m/2)/GAMMA(n/2)*x^(m/2-1)/(1+m*x/n)^((m+n)/2);

In order to calculate the percentage points of the F-distribution we need to find the area under the curve. For example, for known m, n the integral

defines the percentage of points under curve for x, since

This can be done easily in Maple, if we wish to find, say, 95 % confidence level for m=4, n=3, we (could) do the following:

> Fstat:=proc(perc,m,n) fsolve(int(fdist(u,m,n),u=0..x)-perc,x=0..infinity); end proc:

> Fstat(0.95,4,3);

9.117182253

Is there a Maple built-in function I can use to calculate these values in a more elegant form instead of defining fdist and Fstat?

Is there something similar for the evaluation of the percentage points of the t-Distribution?

Graph the surfaces  y= x + z and y = 1 - z on the same axes using the domain |x| < or = 1.2 , |z| < or = 1.2 , and observe the curve of intersection of both surfaces. Show that the projection of this curve onto the xz-plane is an ellipse.

So that's that problem. I am so lost on what to do. I know it has to do something with implicitplot3d.

## Plot Riemann sums for double integals...

I know that student[middlebox] can graph an approximation of an integral.
For example,
with(plots):
with(student):
f:=x->sin(x)+0.2*x+0.5:
a:=0: b:=16: N:=10:
C:=plot(f(x), x=a..b):
R:=middlebox(f(x), x=a..b, N):
display(C,R);

I need to know how to use Maple to do the same plotting for double integrals. Thanks for your help.

## Maple Solve Command...

Hello everyone.

I believe I have come across some kind of bug in Maple 11, and I was wondering if anyone could confirm that I am not crazy and that I am not using the software incorrectly.  When using the solve command, I get some very weird stuff:

evalf(solve(x^3+1/4 = x))

evalf(solve(x^3+.25 = x))

The second gives the correct answers.  The first gives three complex roots.  Am I doing something wrong?

Thanks,

John

## plot both an arrow and a function....

O.k. so I can plot an arrow.  And I can plot a function.  Now how do I get them on the same plot?  Any simple example that shows how to do this will help me.  Thanks.