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mmcdara

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These are questions asked by mmcdara

Seeking for a question about a bouncing ...

mmcdara 7891 Maple , MaplePrimes
ode dsolve numeric
August 31 2019
1 1

Hi, 

does anyone remember of a recent question (maybe a post) about a bouncing ball over a hilly ground?
I can't put the finger on it.

TIA

Why does the tilde operator sometimes fa...

mmcdara 7891 Maple 2015
round map elementwise
August 28 2019
1 2

Hi, 

While trying to convert into integers a sample S drawn from a binomial distribution,  I've observed that  round~(S) didn't do the job while map(round, S) did it.

First question: why the first syntax and the second one are not equivalent on this case?

I investigated a little bit further by applying round~ on a row vector T of Hfloats (thus T and S are "identical")

Second question: While  round~(S) doesn't work but round~(T) does?


 

> 

restart
> 

S := Statistics:-Sample(Binomial(10, 0.5), 2);
round~(S);      # Why round~(S) doesn't return integers
map(round, S);  # but map(round, S) does?

lprint(S)

S := Vector[row](2, {(1) = 6.0, (2) = 7.0}, datatype = float[8])

  

Vector[row]([6., 7.])

  

Vector[row]([6, 7])

  

Vector[row](2, {1 = HFloat(6.), 2 = HFloat(7.)}, datatype = float[8], storage = rectangular, order = Fortran_order, shape = [])

  
> 

# Evaluation of round~(T) on a vector of Hfloats



T := Vector[row](2, [HFloat(6.), HFloat(3.)]);
lprint(S);
round~(T);   # round~(T) returns integers,
             

T := Vector[row](2, {(1) = HFloat(6.0), (2) = HFloat(3.0)})

  

Vector[row](2, {1 = HFloat(6.), 2 = HFloat(7.)}, datatype = float[8], storage = rectangular, order = Fortran_order, shape = [])

  

Vector[row]([6, 3])

 (1)
> 

 


 

Download Tilde_versus_map.mw

 

Statistics fails to reject invalid param...

mmcdara 7891 Maple 2015
statistics
August 27 2019
0 2

Maple doesn't completely check the condition on the number of trials "n" for Binomial and NegativeBinomial distributions (package Statistics).
The attribute "Conditions" explicitely says that n must be a strictly positive integer but no strictly positive real valuereturna an error (ok, it would be stupid to set n to a non integer value !!!).

I think it is a default that ought to be corrected in future releases (this default still exists in Maple 2018)

 

> 

restart
> 

kernelopts(version)

`Maple 2015.2, APPLE UNIVERSAL OSX, Dec 20 2015, Build ID 1097895`

 (1)
> 

with(Statistics):


BINOMIAL DISTRIBUTION

> 

X := RandomVariable(Binomial(n, p)):
L := [attributes(X)][3]:
A := exports(L)

Conditions, ParentName, Parameters, CDF, CharacteristicFunction, Kurtosis, Mean, Median, Mode, MGF, ProbabilityFunction, Skewness, Support, Variance, VariationCoefficient, CDFNumeric, QuantileNumeric, RandomSample, RandomSampleSetup, RandomVariate

 (2)
> 

L:-Conditions

[0 <= p, p <= 1, n::posint]

 (3)
> 

# Maple should return an error for N is not of type posint
#
# It seems that Sample uses floor(N)

N := 10.49; type(N::posint);
P := 1/2:
X := RandomVariable(Binomial(N, P)):
Mean(X), N*P;
ProbabilityFunction(X, k);
S := Sample(X, 10^6):
Mean(S);


# A non consistent result (only non negative values of k should be accepted)

eval(ProbabilityFunction(X, k), k=evalf(Pi));

N := 10.49

  

false

  

5.245000000, 5.245000000

  

piecewise(k < 0, 0, binomial(10.49, k)*(1/2)^k*(1/2)^(10.49-k))

  

HFloat(4.998903)

  

.1096019539

 (4)


NEGATIVE BINOMIAL DISTRIBUTION

> 

X := RandomVariable(NegativeBinomial(n, p)):
L := [attributes(X)][3]:
A := exports(L):
L:-Conditions

[0 < n, 0 < p, p <= 1]

 (5)
> 

N := 10.49:
P := 1/2:
X := RandomVariable(NegativeBinomial(N, P)):

Mean(X)


 

Download BinomialLaw.mw

 

Where does this error come from?...

mmcdara 7891 Maple
geometry plottools
August 23 2019
1 1

Hi, 

I've got this strange error. Could anyone explain me where it comes from?
Thanks in advance.

(PS My Maples's version is  Maple 2015.2, APPLE UNIVERSAL OSX, Dec 20 2015, Build ID 1097895 )
 

> 

restart:
> 

with(plots):
with(geometry):
> 

RegularPolygon(gon,5,point(o,1,1),2);

gon

 (1)
> 

restart:
> 

with(plots):
> 

geometry:-RegularPolygon(gon,5,point(o,1,1),2);

Error, (in geometry:-RegularPolygon) wrong type of arguments

  
> 

 


 

Download ErrorMessage.mw

Is it possible to instantiate all the at...

mmcdara 7891 Maple 2015
statistics distribution
August 05 2019
0 11

Hi, 

When creating a user random variable, I would like to instanciate some of its attributes, for instance ParentName.
But it seems that it's not always possible.

​​​​​​​Is it a Maple's limitation or am I not doing the things correctly ?
​​​​​​​
Example:
 

> 

restart:
> 

with(Statistics):
> 

U := RandomVariable(Uniform(0, 1)):
> 

interface(warnlevel=0):
> 

A := attributes(U)[3]

_ProbabilityDistribution

 (1)
> 

AllAttributes := with(A);

[CDF, Conditions, HodgesLehmann, InverseSurvivalFunction, MGF, MaximumLikelihoodEstimate, Mean, Median, Mode, PDF, Parameters, ParentName, Quantile, RandomSample, RandomSampleSetup, RandomVariate, RousseeuwCrouxSn, Support, Variance]

 (2)
> 

A:-ParentName

UniformDistribution

 (3)
> 

# Define a user random variable

v := Distribution(PDF = (z -> piecewise(0 <= t and t < 1, 1, 0))):
V := RandomVariable(v):
A := attributes(V)[3];
AllAttributes := with(A);
A:-Conditions;

_ProbabilityDistribution0

  

[Conditions, PDF]

  

[]

 (4)
> 

# its definition can be augmented by adding some recognized attributes...
# even if the result returned by Mean is strange

v := Distribution(PDF = (z -> piecewise(0 <= t and t < 1, 1, 0)), 'Mean'=1/Pi, 'Median'=exp(-1)):
V := RandomVariable(v):
A := attributes(V)[3];
AllAttributes := with(A);
[Median, Mean](V)

_ProbabilityDistribution1

  

[Conditions, Mean, Median, PDF]

  

[exp(-1), 1/Pi(_R1)]

 (5)
> 

# but not all the recognized attributes seem to be able to be instanciated:

v := Distribution(PDF = (z -> piecewise(a <= t and t < b, 1/(b-a), 0)), 'Parameters'=[a, b]);
v := Distribution(PDF = (z -> piecewise(a <= t and t < b, 1/(b-a), 0)), 'ParentNames'=MyDistribution);

Error, (in Statistics:-Distribution) invalid input: too many and/or wrong type of arguments passed to NewDistribution; first unused argument is Parameters = [a, b]

  

Error, (in Statistics:-Distribution) invalid input: too many and/or wrong type of arguments passed to NewDistribution; first unused argument is ParentNames = MyDistribution

  
> 

 

 


 

Download Attributes.mw

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