Axel Vogt

5006 Reputation

19 Badges

15 years, 258 days
Munich, Germany

MaplePrimes Activity


These are replies submitted by Axel Vogt

@Carl Love I suppose that on Windows the filename can be catched from system libraries, since the dialog "save as" automatically provides the name

@tomleslie he is using Maple 2019, and in Maple 2020 I get your result without the Physics extension

u(x) = 1/10*piecewise(x < 0,(-1+I+(1+I)*3^(1/2))*5^(1/2)*(22*I*x+(16*x^2+44*x-1
)^(1/2)-I)^(1/6)*2^(1/3)/x^(1/3),x = 0,20,0 < x,2*(-1)^(1/12)*5^(1/2)*2^(5/6)/x
^(1/3)*(22*I*x+(16*x^2+44*x-1)^(1/2)-I)^(1/6))

@vv a neat elaboration!

@ReactionUra 

There may be many reasons for "errors".

For example you provide only a small number of decimals for your constants (4 - 5) while sometimes you provide 16 decimals. It might be better to provide at least 16 for all (and more if it turms out that higher precision is used) to reduce rounding errors

This is a bit related to a mathematical fact: generically you can expect discrete solutions if using n=13 equations and n variables (discrete = isolated n-tuples in n-space each giving a solution). But even if there would be only discrete solutions there might be none, especially over the Reals (think pf a parabola).

And if feeding the solutions there will be a (numerical) error. One has to judge whether it can be accepted or not - for example a very steep function with a zero z0 may have a large absoluet error in that while it can be accepted because it is small in a relative sense (and the "best" approximation).

From you last eq13 and your remark "must be positive" it follows that u_C1 is between ionic=0 and ionic=infinity, i.e. roughly between 0.58 and 0.97

As far as I can see you want to solve something like exp(r*x)= a*x^2 + b*x + c. You can not expect a "closed" form (but you can do it using fsolve after feeding numerical values for you parameters)

@CR 

Do not use data frames.

I converted your CSV to xlsx (and corrected the field name)

For your large file I get the error "Error, (in ExcelTools:-Import) out of memory error while processing result" in Maple 2017, for 2020 it results in some non-processing without error message or warning, for your smaller file it works, in both cases I used the standard interface (*.mw)

So - as you guessed - the file may be too large (at least for my machine)

Your link does not work for me, may be it uses services which have blocked for my machine or through my firewall

@CR 

Excel only displays you some date format, but actually uses floats.

Find attached a decomposition into year, month etc and the import to Maple. I did that using my country settings = Germany

Example_229991.xls
MP_229991.mws

Added: And your large file has an encoding error, the first entry is not the name "Data", it is "Data" so it is likely an error by generating that csv and Maple can not interprete that field name

@Carl Love therefore I would call it a respectable bug

@CR , you screenshots indicate that you may have a formatting problem for the name of the field "data" = date in your large file.

Why dont you just import as Excel file and convert to another type like a DataFrame later on?

Anyway your time stamps in the field "data" as string will possibly help you not much in Maple.

A common way is: split in year month day and parts of a day on the source, here it is Excel and it has functions for that (NB: internally Excel on a sheet just uses floats and only a 'mask' displays it as date)

Int(Dirac(sin(x)),x=-1..1); value(%); returns unevaluated as well (Maple 2020)

The file seems to be too large for the amount of data (and contains formulas as well). I saved it again using Libre Office, now it is 500 KB instead of 12 MB. May be you try again with that. Also you may check whether the versions of Maple and Excel are valid as pairing.

Subset_test1.zip

Edited: for me then it works (no need to change country settings) using Maple 2020 with Standard Interface

with(ExcelTools);
Q:=Import("d:\\temp\\Subset_test1.xlsx"); # giving a 1300 x 90 Matrix

You may have to convert the date format, have not looked for you formula fields

Just a thought: if you work with Windows settings for Italy (?) then time format and floating point numbers are not what Maple is expecting. You may (temporarily) change to US for your Windows (or process data through editing which is a little pain).

I have not tested it for your case.

I do not think that does make sense, look at the graphics at https://en.wikipedia.org/wiki/History_of_the_Internet#Rise_of_the_global_Internet_(late_1980s/early_1990s_onward) which is for hosts, not users. Hence I guess it is a "S-shaped" curve and in logarithmic scaling it may have a chance to be roughly quadratic "at current end". And you may wish to have some (guessed) data, of course.

And in the ghist of mmcdara

Fac:= n -> mul( i, i = 1 .. n ); # https://rosettacode.org/wiki/Factorial#Maple

Fac(5)=5!;
                              120 = 120

 

 

@mmcdara Thank you, but it's Maple's solution :-) Unfortunatly quite hidden, I just remembered that I once used it

For your question: sorry, I do not know an answer for that.

1 2 3 4 5 6 7 Last Page 1 of 194