OK, so ive solved a pde numerically. I can plot the solution as a graph, evaluate the value at different times, but how can I integrate it over the region it is defined? My goal is this, the weighted average of x:

Can alone explain to me what is happening in this procedure? I know it is it is to generate a line p and an angle theta but don't understand what line and angle or how it does it.

Im having trouble with the DEplot command, i seem never to be able to use the plot commands on maple no matter what i do. Heres what i've got so far. > eq1 := diff(n(t), t)+lambda*n(t) = 0; / d \ |--- n(t)| + lambda n(t) = 0 \ dt / > eq2 := dsolve([subs(lambda = .1, eq1), n(0) = 10]); / 1 \ n(t) = 10 exp|- -- t| \ 10 / > with(DEtools);

In the help, it writes

BesselJ and BesselY are the Bessel functions of the first and second kinds, respectively. They satisfy Bessel's equation:
     2                2    2
    x  y'' + x y' + (x  - v ) y = 0
 

My problem is in statistics. I'm looking for the resulting normalized distribution funtion.

Given a sample has a normal distribution of trait A, and given a subgroup that posseses trait B with a different normal distribution of trait A. Waht would the distribution of trait A be if we eliminate the subgroup that posseses trait B.

The following example that assumes a subgroup of 20% does not yield the proper result.

f := x -> if(x<=0, 0, 1):
#plot(f(x),x=-10..10):
#plot(f,-10..10):
plot(sum(f,i=-infinity..infinity),-10..10);
plot(sum(f(i),i=-infinity..infinity),-10..10);

Why do the first two plots work, but the third and fourth doesn't? How do I plot the sum of this function in a specific range?

How do I get a closed-form expression?

I tried the following (e.g.):

 

> k[21] := t-> piecewise(t<0,0,p*(1-p)^t);                      {definition of descrete probability distribution, here: geometric distribution}

I want  to calculate the derivative of Bessel, I do

Dear Maple Experts,

  I'm fairly new to Maple.  I've been trying to compute Gaussian tail probabilities accurately.  As I understand it, Maple has an "erf" function, but not an inverse erf.  Other posts have suggested doing something like:

  inv_erf := x->solve(erf(y/sqrt(2.0))=x,y);

At first ; for instance, about 68% of a Gaussian's probability is within 1 standard deviation, so:

> erf(1/sqrt(2))

    0.6826894920

> evalf(inv_erf(0.6826894920));

    0.9999999994

So far, so good.  Unfortunately, my interest lies in fairly large deviations (up to about 9 standard deviations).  All of a sudden, I start to get complex (!) answers:

> evalf(inv_erf(1-(10^(-16))));
                                 8.304785423
> evalf(inv_erf(1-(10^(-17))));
                         -3.937718724 - 4.575448791 I
 

I've tried using "erfc" instead of "erf", under the logic that it might be better at estimating the tails, but it doesn't seem to resolve the problem.  What's going on and how do I fix it?

  Thanks for any help.

 

Hi everyone, I have question that i cannot solve.

The question is : 

Write a procedure named MULTIPLYMATRIX to find the product of an n x m matrix by an
m x q matrix. Your procedure should print the result matrix. The dimensions n, m, q should be
input parameters in your procedure. Test your procedure by demonstrating multiplication of a 2 x
3 with a 3 x 4 matrix of your choice.

 

I mean when typing polynomials, convert the 2x4 to 2x^4,,,

for 4 is in the right

and sometimes I'm a little lazy(?).

...

p1:=4*y^2+12*y-4*x*y-6*x+x^2+8

a is "coeffs(p1)"

b is "coeffs(coeffs(p1, {x, y}))"

c is "coeffs(p1, [x, y])"

d is "coeffs(p1, x)"

e is "coeffs(p1, x, y)"

the results of a,b,c are the same

8, -6, 12, 4, 1, -4

and the results of d,e are the same

4*y^2+12*y+8, -4*y-6, 1

question 2:

I'd like to get the both resuls of "coeffs(p1, x)" and "coeffs(p1, x)" at the same time,

what's the simplest way?

Hi

I have some calculations/results which I use in many other documents. Is there anyway to link to this document that contains results I need for another sheet in the beginning of the sheet I need the calculations for?

 

Thanks in advance

Regards Brian

How do I write a loop to store a set of values for t and n(t) into an array?

 

I wrote a loop to get the values:

>for t  from 1 by 1 to 25  do print(t, f(t)) end do

 

but don't even know where to begin with putting them into an array.

Thanks for any help.