erik10

I have a degree in Mathematics and Physics from the Danish University Aarhus, comparable to a masters degree with thesis - majoring in Mathematics. In 1991-92 I was a visting scholar at UCLA, Los Angeles, following graduate courses in Applied Mathematics. Since 1992 I have been a teacher in a high school (gymnasium) in Denmark. Special interests: Applied mathematics, graphics and popularizing Mathematics.

MaplePrimes Activity


These are questions asked by erik10

Dear Maple users

I am unsure how to handle events and their probabilities in Maple. Let's say I know that an event A has the probability say 0.3 and another event B has probability 0.8. I would like to make the following assignments:

P(A):=0.3:

P(B):=0.8

and maybe defining the conditional probability:

P(A|B):=0.55

but I am not allowed to do so in Maple because if will regarded as a function definition. My purpose is to make simple calculations with those probabilities for example:

P(C):=P(A)*P(B)  etc.

My problem is therefore more of a notational problem than a mathematical one. I hope someone can advice me on a proper setup. I am using 2D math notation, by the way. I could of course name the variables containing the probability using simple names like X1, X2, etc., but then I need constantly to remember what they really mean. The above assignments would be much better, because they are easier to handle mentally.

Regards,Erik

I need to make a lot of similar calculations and wonder if it can be done in a smart way in Maple. Microsoft Excel is perfect for this kind of calculations, because you can downcopy cells. I would like to do everything in Maple, if possible, though. I have a number of points A, B, C, D, E, ... , which all lie on various circles in the plane. For every point radius and angle is given, so actually you can say that every point is delivered with polar coordinates. I want to have their rectangular coordinates. 

Maybe I could deliver their radii in a list and their angles in degrees in another list?

r:=[12,56,29,...., 78]:

v:=[15,45,75,..., 102]: 

......

I need to be able to refer to a certain point thorugh an index. At best it would be A, B, C, ... , but 1, 2, 3, ... will be acceptable. So in the end I need to be able to access say x_C and y_C or x_3 and y_3 (understood as index lowered). I hope someone can help me do the task in a nice a efefctive way.

NB! Maybe you have a solution, which involve transformation from polar to rectangular coordinates. That will be nice, but please also tell me how it can be done from scratch, because I want to be able to know about handling many points at once for other purposes, when the function is not r*cos(v), but an arbitrary function.

Regards,

Erik

Dear Maple users

I have a question which is maybe easily solved, but I cannot seem to find the solution myself. A vector X of coefficients has been computed earlier in the Maple document and I want these coefficients placed in front of some written symbols in order to make Maple display the final result in a nice way. I made an attempt with the Vector command as shown in the image, but I cannot make the indices start at -2. In addition I want some written math placed in front of the expression. In fact I want it displayed like shown on the image marked with a red rectangle. I did write this manually, but want Maple to do it automatically when given the coefficients vector calculated earlier. I hope someone can help me here!

(It is about finite difference methods, by the way)

 

Regards,

Erik 

Dear Maple users

My question is probably simple, but I can't seem to figure out how to do it in a smart way way without using procedures: My task is to create a cumulative list from a list. Ex: From [3,-2,5,1,10,7] I want to create the list [3,1,6,7,17,24]. Every entrance in the new list is the sum of the previous ones including the actual entrance. The Statistics package contain a command named CumulativeSum, but unfortunately a list is not returned ... I hope someone can help doing it is a simple way.

Regards,

Erik

The built-in Histogram command in the Statistics package only creates a Histogram from raw data, unfortunately. There is however a big number of situations, where you only have grouped data with intervals and their associated frequencies (probabilities) and want to plot the Histogram. Suppose that the intervals are of equal width and (indirectly) are specified from a starting point x0, a column-width named 'width' and the number of intervals given by n. Suppose the frequencies...

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