janhardo

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MaplePrimes Activity


These are questions asked by janhardo

restart;

f:=(x,y)->x^4-3*x^2-2*y^3+3*y+0.5*x*y;

proc (x, y) options operator, arrow; x^4-3*x^2-2*y^3+3*y+.5*y*x end proc

(1)

 

Critical points: tangentline in x direction and y direction are  0  for some points on the surface  f(x,y)  

 

CriticalPoints:= [ solve( {diff(f(x,y),x)=0,diff(f(x,y),y)=0}, {x,y}) ];

[{x = 0.5935572277e-1, y = .7105957432}, {x = 1.191117672, y = .7741187286}, {x = 1.255942703, y = -.7776000848}, {x = -0.5877159444e-1, y = -.7036351094}, {x = -1.197482099, y = -.6326213916}, {x = -1.250162405, y = .6291421140}]

(2)

         

Seems that maple calculate 6 points on the surface with a default domain?

let me make a  3D plot of f  ( not specifying the domain values)

plot3d(f);

 

 

I calculated 6 critical points :how to show them in the plot? : i calculate the functionvalues for f
So now i do have x,y,z values for a 3D point
plot3D ({ f, points}) ?

?student

 

Some information to find in

• 

 Student[MultivariateCalculus]  ..link?

• 

Multivariate Calculus Study Guide

In order to make a procedure ( to make it general) out of the wanted calculated steps , i must first calculate these steps
List of wanted steps:

1. 

calculate (6 )critical points : i did

2. 

investigate of the found critical points :are there saddle points among them?
Show this in a table

3. 

show a critical point with 2 section lines in this critical point intersected in a plot

4. 

show these critical points in a plot

===========================================

How to make table out of this list.CriticalPoints. for easy reading.?

==========================================

CriticalPoints:= [ solve( {diff(f(x,y),x)=0,diff(f(x,y),y)=0}, {x,y}) ];

[{x = 0.5935572277e-1, y = .7105957432}, {x = 1.191117672, y = .7741187286}, {x = 1.255942703, y = -.7776000848}, {x = -0.5877159444e-1, y = -.7036351094}, {x = -1.197482099, y = -.6326213916}, {x = -1.250162405, y = .6291421140}]

(3)

 

Download zadelpunten_procedure.mw

"Taking a list of numeric values L, and producing a list of lists [p,f(p)] for every p in L , is not complicated. In fact it is a quite straightforward and rather basic example of Maple programming"

This sentence i don't understand yet, so i must see a example?

On my maple page i got also all the time typesetting info ?
Looked at the help page :NumberTheory,PrimeCounting

How to produce the graph of the prime counting function with the two approximations?

When should i use ->  for a procedure definition and when not ?
In my post i do see examples of  procedures which are made on two different ways.
proc  ..end proc;

Still difficult to get a procedure on two ways 

test:=x->x^2;
Typesetting:-mprintslash([(test := x -> x^2)],[x -> x^2])

test(2);
4

restart;
test:= proc()
local x,a;
a:= x^2;
end ;
Typesetting:-mprintslash([(test := proc () local x, a; a := x^2; end proc)],[
proc () local x, a; a := x^2; end proc])

test(2);
x^2

test(3);
x^2

As you can see with the standard proc definition i getlost with  calculating x^2 

Can i make a natural numberline what shows the enumber of primes at each of 1000 numbers  
I have her

0-1000 : 168
1000 -2000: 135

2000-3000 : 127

3000- 4000: 120

4000 -5000 : 119 

then a gap (jump) 

10^7- 1000- 10^7  : 53 

You can see that the "number of primes"  is fluctuating
Can i make a procedure what calculates the latest mersenne prime number ?
Problem is only that there is a theorem: there are arbitrary long series of divisible numbers on the numberline 
There are gaps of length n - 1, where are no primenumbers  in positioned.

The idea is to get a idea of the distribution of primes to make a guess from where to start to find another one? 

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