662 Reputation

18 years, 104 days

Double and multiple integrals...

Mario,

Please see the help page by entering ?int. This gives an example of a double integral. In future it would be easier to understand what help you need if you could  write out your problem more fully.  Guessing at what your first example means, I tried this:

restart;
Int( Int(x^2 + y^2,x=y-a..y), y=3*a..a);
value(%);

Hope this helps,

J. Tarr

dsolve...

Please see the help page ?dsolve and its examples.

Hope this helps.

J. Tarr

Free...

Chen,

You might find http://integrals.wolfram.com/index.jsp useful. It's free and you will need pencil, paper and a little thought to get the answers you want.

For example

Int(exp(x^(-2), x) is given as (1/2)*sqrt(Pi)*erf(x).

Since erf(infinity) = 1 and erf(0)=0, the answer you want is

(1/2)*sqrt(Pi)

Hope you find this helpful.

J. Tarr

Fit...

Please see ?Statistics[ExponentialFit] and first example. ExponentialFit tries to fit y = a * exp(b * x) to the data. It doesn't necessarily produce a good fit - in your example LeastSquares(x,y,t,curve=a*exp(-t) + b*t +c produces a better fit.

Hope this helps.

J. Tarr

primes...

Hope that's what you need.

J. Tarr

Curve Option...

Please see third example at ?CurveFitting[LeastSquares].  I assume that you want to use an exponential as your curve.  If so try this:

restart;
x := <0.0, 1.0, 2.0, 3.0, 4.0, 5.00, 6.00, 7.00, 8.00, 9.0>:
y := <4.1, 1.3, 0.4, 0.3, 0.1, 0.08, 0.07, 0.06, 0.08, 0.1>:
p1 := plots:-pointplot([seq([x[i],y[i]],i=1..9)]): ##Plot points(Measured values )
sol2 := CurveFitting:-LeastSquares(x,y,t,curve=a*exp(-t) + b*t +c): ## get optimal val
p2 := plot(sol2,t=0..8):
plots[display]([p1,p2]);

Hope this helps.

J. Tarr

Display Arrays of plots...

Please see ?plots[display] second calling sequence and examples with Arrays of plots. Something like this should do what you want:

A := Array(1..2):
A[1] := inequal({x-y <= 1, x+y > 0}, x = -3 .. 3, y = -3 .. 3, optionsfeasible = (color = red)):
A[2] := inequal({y < 0, x < 0}, x = -3 .. 3, y = -3 .. 3, optionsfeasible = (color = blue)):
display(A);

J. Tarr

Do you want to...

Do you want to differentiate

y(x)^2+(x-c)^2=c^2 w.r.t.  x ? Try

diff(%,x).

J. Tarr

Pi...

Try this

Int( (sin(x))^2/x^2, x=-infinity..infinity);
value(%);

Perhaps your limits are wrong.

J. Tarr

Chemistry...

Take a look at the Maple Application Center in the section Science:Chemistry and you should find something to get you started. Good luck,

J. Tarr

fsolve...

If you assign your equation to eq, you could use fsolve, like this

fsolve(eq,{P},P=0..2);

{P=0.527727062715}

Hope this helps

J. Tarr

tagliatelle...

The html tags have messed up Robert Israel's suggestion.  Isn't it time that this problem was sorted?

Getting back to Maple, I tried greater than symbols and obtained plots, but with the error message:

Warning, unable to evaluate the functions to numeric values in the region; see the plotting command's help page to ensure the calling sequence is correct

What's the reason, please?

J. Tarr

J. Tarr

Precisely...

Jacques,

Thanks for emphasizing my point. One could take it further and say that Maplesoft needs to get a firmer grip on new development, who it's for (many or minority) and is it just bloatware. Maybe you'd like to start a poll on the most useful parts/packages in Maple 11 to give Maplesoft a better idea of what it's customers really want.

J. Tarr