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For example, i have the field x*e_x+y*e_y. Is there a command for transforming it into the same field with polar coordinates and polar unit vectors?

Hi,

I would like to calculate the inverse fourier transform from this: 

And I get this:

I'm looking for a simple way, e.g. a function, to convert a system of symbolic equations in its matrix form.

Like

(a+1)x - by + cz = j

2x  + (sqrt(d)+e)y - fz = k

(g-h²+1)x - iy - 4z = l

shall be transferred to matrix / vector form

A . x = b

where A i the matrix of the coefficients, x i the vector of the variables (x,y,z), and b is the right-hand-side vector (j,k,l).

The number of equations...

Hi,
Consider the following DEQ:

x*y'+2y=1

Maple can solve this without problems with dsolve. But I want to use the Mellin Transformation for this, similar to the more common laplace transformation. The last step, the transformation back to the x-domain, does not work. Any idea why?

restart:with(inttrans);
mellin(x*diff(y(x),x)+2*y(x)=1,x,s);
solve(%,mellin(y(x),x,s));
invmellin(%,s,x);

Thanks

How would you transform a 3D plot structure into a 2D plot structure? I have in mind 1) creating a 3D plot with odeplot or with plot3d, 2) selecting (say) 4 orientations, 3) transforming each into a 2D plot, 4) exporting the 2D plots using the Standard GUI.

The reason behind my question is that the best-looking exported plots that I have been able to obtain with Maple are 2D plots exported as postscript with the Standard GUI. 3D plots don't look nearly as good when...

I am trying to solve differential equation, solve for y(t) if all initial conditions are zero. Use the Laplace transform.

d^2y/dt^2+12dy/dt+32y=32u(t)

Thanks in advance

I was recently looking at rotating a 3D plot, using plottools:-rotate, and noticed something inefficient.

In the past few releases of Maple, efficient float[8] datatype rtables (Arrays or hfarrays) can be used inside the plot data structure. This can save time and memory, both in terms of the users' creation and manipulation of them as well as in terms of the GUI's ability to use them for graphic rendering.

What I noticed is that, if one starts with a 3D plot data structure containing a float[8] Array in the MESH portion, then following application of plottools:-rotate a much less efficient list-of-lists is produced in the resulting structure.

Likewise, an effiecient float[8] Array or hfarray in the GRID portion of a 3D plot structure gets transformed by plottools:-rotate into an inefficient list-of-lists object in the MESH portion of the result. For example,

restart:

p:=plot3d(sin(x),x=-6..6,y=-6..6,numpoints=5000,style=patchnogrid,
          axes=box,labels=[x,y,z],view=[-6..6,-6..6,-6..6]):

seq(whattype(op(3,zz)), zz in indets(p,specfunc(anything,GRID)));
                            hfarray

pnew:=plottools:-rotate(p,Pi/3,0,0):

seq(whattype(op(1,zz)), zz in indets(pnew,specfunc(anything,MESH)));
                              list

The efficiency concern is not just a matter of the occupying space in memory. It also relates to the optimal attainable methods for subsequent manipulation of the data.

It may be nice and convenient for plottools to get as much mileage as it can out of plottools:-transform, internally. But it's suboptimal. And plotting is a topic where dedicated, optimized helper routines for some particular data format is justified and of merit. If we want plot manipulation to be fast, then both Library-side as well as GUI-side operations need more case-by-case-optimizated.

Here's an illustrative worksheet, using and comparing memory performance with a (new, alternative) procedure that does inplace rotation of a 3D MESH. plot3drotate.mw

Hi! A question regarding animating a rotation transformation defined by plottools[transform]. I can get the shear, translation and stretch to be animated. But when I use the same commands for rotation, the output doesn't appear. Here are my commands attempting to animate the rotation:

with(plots):

with(plottools):

with(LinearAlgebra):

p:=plottools[rectangle]([0,1],[1,0])

g:=transform((x,y)->convert(Multiply(Matrix([[cos(r), sin(r)...

Hey there

I got a little problem.

I would like to have the positive numbers on the y-axis to point downworth, and of couse the negative going upworth. Is that even possible? 

Hope you can help.

Thanks

I have a sample waveform of an air conditioner and want to see if any low frequencies (10 Hz which is harmful to human health) exist in the wave.  How can I do that?

Granted the frequencies picked up in the recorded file depend on the quality of the recording and the recorder and lower frequencies may not have been picked up. 

I've looked at