## MaplePrimes Questions

Hi, does anyone know if it is possible to use maple to handle equations involving differential forms (antisymmetric tensors). Basically i have a set of equations that involve forms of various degrees, with some indices contracted with vectors etc. Now most of the components of the forms are zero, but the equations are still very tedious to handle by hand. It would be useful if i could input the equation into maple, tell it all the various non-zero form components, and then let maple substitute the components into the equation. Naturally i would need to specify the values of the free indices in the equation, so that the tensor equation reduses to a standard equation. And presumably Maple would need to understand the einstein summation convention etc.

## Convert 1 + 0.I to 1...

What is the proper method for converting an extended numeric with a zero imaginary component to a real? It should leave the complex part alone if it is not zero. That is, somefunc(1.0 + 0.*I); 1.0 somefunc(1.0 + 1.*I); 1.0 + 1.*I I can write my own procedure, but there must be standard way (somefunc) to do this. Searching the help browser didn't help. Thanks.

## sending multiple mails...

I want to know how to send mails to multiple email addresses using PHP code. Thanks. http://www.hytechpro.com

## search...

what's the command to find if 2 is an element of {1,2,3,4,5,6,7} to return true?

## get default math input in worksheet format...

How can one set math as the default input mode for a worksheet when using Maple Input notation? I find that creating a new execution group always puts me back in text mode. Of course, I fail to notice this and enter math expressions with annoying results. 2-D Input Notation will remain in math mode. I am using OS X (10.3.9).

## Constrained optimization...

Hi, I am trying to solve a maximization problem using the following Lagrangean: L:=v*K*a^gamma*k^(1-gamma)-1/2*a^2-1/2*k^2 -1/2*r1*v^2*sigma^2-1/2*r2*(1-v)^2*sigma^2 -mu*(v*K*gamma*a^gamma*k^(1-gamma)/a-a) -lambda*((1-v)*K*(1-gamma)*a^gamma*k^(1-gamma)/k-k) I first computed the partial derivatives for a, k, v, mu and lambda (La:=diff(L,a)=0, Lk:=diff(L,k)=0, ...). (K, gamma, r1, r2 and sigma are constants) Then I applied solve ({La,Lk,...},{a,k,v,lambda,mu}) and did not get any result (or message) back. I already tried to solve this problem by step-by-step calculations, but was not successful in getting solutions for a, k and v (stated in terms of gamma, r and sigma). When I make the problem simpler (by setting r1:=0 and r2:=0) I get a solution.

## Creating Solids of Revolution...

Can Maple be used to create solids of revolution by rotating intersecting plane curves or a single curve bounded by certain intervals about lines or the cartesian axes ? If yes can someone help with the steps to accomplish this ?

## a problem with fsolve...

hi how i get all the roots? > fsolve('P2(x)=0',x=0..1); 0.7653758275 > fsolve('P2(x)=0',x=0..0.6); 0.1740920943 > fsolve(P2); 4.274188187 i need the smallest root and P2(x) is numerical solved it's not continius

## strange thing with sqrt...

pls check the attached worksheet ... any reason for that behaviour?

PS: not attached due to some oddity of the forum software,
"Error attaching file 102_strangeRoot.mws: exceeds maximum file size"

so take it from http://www.axelvogt.de/maplekram/strangeRoot.mws
(or *.zip if perfered, it is below 4 kB anyway ...)

## How do I curve fit data to this form?...

I'm trying to figure out how to fit the data below to a curve of the form: a+b*sin[(pi*x)/6-c] How do can I do this in Maple 10? 1,43.2 2,47.2 3,53.7 4,60.9 5,70.5 6,82.1 7,88.0 8,86.0 9,77.4 10,66.0 11,51.5 12,44.1

## Inserting two columns into text...

Is it possible with Maple 10 to change a document so that in the middle, there are two columns? One might imagine having some text describing how data was gathered where the text is spread over the usual six inches or so. Reading on down the document, the style might change to two columns: a graph of the data in the right column and comments on the data in the left. After this, the document could revert to the normal six inch, full line text. Did I not see something such as this in a demo at the Maple Summer Conference?

## extract the z value of a 3dplot...

I want to display a 3dplot of a current

iL_RMS_3dplot_Ue_const:=plot3d(iL_RMS_func_Ue_const, 0..2, 0..1, axes=normal, title="RMS current through the inductor with Ue constant and Ua variable", labels=["Ia_IaLGmax", "Ua_Ue", "iL_RMS_Ue_const"]);

together with an output curve. The output curve (which is two dimensional) should have as the z value in a 3d plot the value of iL_RMS_3dplot_Ue_const at that place. I have uploaded an example to http://www-users.rwth-aachen.de/Kai.Schueler/3dplot_example.jpg (the blue curve is the output curve). Is it possible, without recalculating the z value with a function to call, to extract it from the iL_RMS_3dplot_Ue_const plot data structure with an op command or something similar. The 3dplot command for the output curve should look somehow like this:

## get Maple to use full evaluation in a function cal...

I don't understand, why maple has problems with the following command:

Output_Curve_test:=plot3d([0,0,iL_RMS_func_Ue_const(Iatest,U_test)],Iatest=0..2,U_test=0..1);

It seems that Maple doesn't call the funciton iL_RMS_func_Ue_const with the function variables Iatest and Utest. Instead it just uses the variable names Iatest and Utest. I get the error message:

Error, (in iL_RMS_AVG) cannot determine if this expression is true or false: 46.87500000*Iatest <= .1250000000*(1500-1500*U_test)*U_test

How do I get Maple to use the actual Values of Iatest und U_test? Below are the functions which are related to the problem.