nm

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13 years, 176 days

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These are questions asked by nm

I was searching release notes for some old Maple versions. I found so many broken links on Maple web pages. The first page is https://www.maplesoft.com/products/maple/history/ 

Scrolling down, and starting from Maple 2016 (about half way down the page), all links to the "product press release" are broken. This is the link to the right of each product.  All these links on the right, from 2016 to the end of the page are broken,

Clicking on any of these, sends the user to new broken web page, called https://www.maplesoft.com/company/publications/  titled "Maplesoft media coverage".

This page does not even work. Clicking on "Jump to year" does not open. Clicking in "first page" does nothing. Tried Edge browser on windows 10, also the page does nothing. 

Then I clicked on Maplesoft Media Releases link at top, and now it works.

But jumping to any year before  2016, all the links that show on those pages are broken. Try and see,

For example. jumping to 2015, and clicking on release called "

November 25, 2015"

Gives

This applies to each press release for each year from 2015 to 1997.

Hundreds of links are broken.

There is software which checks broken links, and it is free for windows, called Xenu's Link Sleuth. May be someone at Maplesoft can use it to find all broken links at Maplesoft web site and fix them?

It is not acceptable in this day and age to have a Major software company with a web site full of broken links.

Do not know if this known or reported or not. Just in case. Here is an example where odetest gives internal error when adding integer to assuming. 

Maple 2025.2. Firewall will not let me upload now. Here is code

sol:=y(x) = -4/9*I*(x+1)^(1/4)*(x-1)^(1/4)*2^(1/2)*x^2+4/9*(x+1)^(1/4)*(x-1)^(1/4)*2^(1/2)*x^2+4/9*I*(x+1)^(1/4)*(x-1)^(1/4)*2^(1/2)+1/9*x^4-4/9*(x+1)^(1/4)*(x-1)^(1/4)*2^(1/2)-16/9*I*(x+1)^(1/2)*(x-1)^(1/2)-2/9*x^2+1/9;
ode:=(-x^2+1)*diff(y(x),x)+x*y(x) = x*(-x^2+1)*y(x)^(1/2);
IC:=y(0) = 1;

odetest(sol,[ode,IC]) assuming integer,positive;

Screen shot

There used to be specific web pages, that lists specific update to Maple DE solver.

Only ones I can find are from version 8 to 16. Here are the links below. They start by saying this 

https://www.maplesoft.com/support/help/Maple/view.aspx?path=updates/Maple8/de

https://www.maplesoft.com/support/help/Maple/view.aspx?path=updates/Maple9/de

https://www.maplesoft.com/support/help/Maple/view.aspx?path=updates/Maple10/de

https://www.maplesoft.com/support/help/Maple/view.aspx?path=updates/Maple11/de

https://www.maplesoft.com/support/help/Maple/view.aspx?path=updates/Maple12/de

https://www.maplesoft.com/support/help/Maple/view.aspx?path=updates/Maple13/de

https://www.maplesoft.com/support/help/Maple/view.aspx?path=updates/Maple14/de

https://www.maplesoft.com/support/help/Maple/view.aspx?path=updates/Maple15/de

https://www.maplesoft.com/support/help/Maple/view.aspx?path=updates/Maple16/de

But these do not works for anything after Maple 16 and before 8. i.e. changing the number in the link to 17 or 18 and so on, gives no page found error.

All my search leads to no result.

Are such help pages still present for updates to DE solvers in Maple for versions after Maple 16? WHat link to use to access them?

When I look at web pages under "what is new" it also does not have specific section just for DE solver like those pages had. For example   https://www.maplesoft.com/support/help/maple/view.aspx?path=updates%2Fv2025  does not have specific section just for DE solvers.

I wanted to trick odetest and see what it does. I gave it solution to ode with IC. The solution was in form of implicit solution.

odetest verified it.

Then I solved for y(x) from the implicit solution and passed each now explicit solution to odetest, now it does not verify either one. (two explicit solutions resulted)

I would have thought that odetest to not verify the implicit solution as well. Is this a bug or an expected behavior when using implicit?

Does this mean, to be safe, one should try to solve for y(x) explicitly before using odetest? But sometimes this can be expensive or not possible nor practical to do as implicit solution can be complicated to solve for y(x).

Maple 2025.2 on windows 10.

Firewall now suddently will not let me upload a worksheet again for some reason. Firewall did not have a problem yesterday, but today it complained.

So here code and screen shot

restart;
ode:=2*y(x) + 2*x*y(x)^2 + (2*x + 2*x^2*y(x))*diff(y(x), x) = 0;
IC:=y(0) = 1;
maple_sol:=dsolve([ode,IC]);
#                         maple_sol := ()

my_sol_1:=x*y(x)*(2+y(x)*x)=0;
odetest(my_sol_1,[ode,IC])

#                             [0, 0]

PDEtools:-Solve(my_sol_1,y(x));
map(X->odetest(X,[ode,IC]),[%])

#   [[0, 1], [0, undefined]]

I noticed today only 2 cases where calling simplify, with no options, made things worst.

Just trying to understand why.

Here is one example. Solved an ode. when calling odetest on this solution, it gives zero. But if the solution is simplified first, then odetest no longer gives zero. And it is actually hard to find a trick to make it become zero so far.

But the question is: Is this to be expected sometimes? I use simplify sporadically, but like to get smaller  expression at one point. But now I am not sure if I should even do that.

Could this be a problem in simplify itself somehow?

Here is an example.

interface(version);

`Standard Worksheet Interface, Maple 2025.2, Windows 10, November 11 2025 Build ID 1971053`

restart;

ode:=diff(y(x), x) = y(x)*(-1 - x^(2/(ln(x) + 1))*exp(2*ln(x)^2/(ln(x) + 1))*x^2 - x^(2/(ln(x) + 1))*exp(2*ln(x)^2/(ln(x) + 1))*x^2*ln(x) + x^(2/(ln(x) + 1))*exp(2*ln(x)^2/(ln(x) + 1))*x^2*y(x) + 2*x^(2/(ln(x) + 1))*exp(2*ln(x)^2/(ln(x) + 1))*x^2*y(x)*ln(x) + x^(2/(ln(x) + 1))*exp(2*ln(x)^2/(ln(x) + 1))*x^2*y(x)*ln(x)^2)/((ln(x) + 1)*x);

diff(y(x), x) = y(x)*(-1-x^(2/(ln(x)+1))*exp(2*ln(x)^2/(ln(x)+1))*x^2-x^(2/(ln(x)+1))*exp(2*ln(x)^2/(ln(x)+1))*x^2*ln(x)+x^(2/(ln(x)+1))*exp(2*ln(x)^2/(ln(x)+1))*x^2*y(x)+2*x^(2/(ln(x)+1))*exp(2*ln(x)^2/(ln(x)+1))*x^2*y(x)*ln(x)+x^(2/(ln(x)+1))*exp(2*ln(x)^2/(ln(x)+1))*x^2*y(x)*ln(x)^2)/((ln(x)+1)*x)

sol_1:=dsolve(ode);

y(x) = exp(-(1/4)*x^4)/(x^(-2*ln(x)/(ln(x)+1))*exp(-(1/4)*(x^4*ln(x)+x^4+4*ln(ln(x)+1)*ln(x)-8*ln(x)^2+4*ln(ln(x)+1))/(ln(x)+1))*ln(x)^2+2*x^(-2*ln(x)/(ln(x)+1))*exp(-(1/4)*(x^4*ln(x)+x^4+4*ln(ln(x)+1)*ln(x)-8*ln(x)^2+4*ln(ln(x)+1))/(ln(x)+1))*ln(x)+x^(-2*ln(x)/(ln(x)+1))*exp(-(1/4)*(x^4*ln(x)+x^4+4*ln(ln(x)+1)*ln(x)-8*ln(x)^2+4*ln(ln(x)+1))/(ln(x)+1))+ln(x)*c__1+c__1)

odetest(sol_1,ode)

0

sol_2:=simplify(sol_1);

y(x) = 1/((ln(x)+1)*(exp((1/4)*x^4)*c__1+1))

odetest(sol_2,ode);

c__1*x^(ln(x)/(ln(x)+1)+3/(ln(x)+1))*exp(2*ln(x)^2/(ln(x)+1)+(1/4)*x^4)/((ln(x)+1)*(exp((1/4)*x^4)*c__1+1)^2)-c__1*x^3*exp((1/4)*x^4)/((ln(x)+1)*(exp((1/4)*x^4)*c__1+1)^2)

 

 

Download why_simplify_changes_things_at_dec_27_2025.mw

Notice how much simpler the solution becomes after calling simplify. I'd like to use that. But for some reason, odetest now fails to verify the simpler version. Which tells me simplify did something which made the solution not valid.

Here is second example, where calling simplify in betwen did not give zero as expected.

restart:

f := sqrt(1 + sin(x)^2);
F := int(f, x):
df := diff(F, x):
simplify(df - f);

(1+sin(x)^2)^(1/2)

0

restart;

f := sqrt(1 + sin(x)^2);
F := int(f, x):
F := simplify(F):
df := diff(F, x):
simplify(df - f);

(1+sin(x)^2)^(1/2)

-csgn(1, cos(x))*sin(x)*EllipticE(sin(x), I)

 

 

Download why_simplify_changes_things_at_dec_27_2025_V2.mw

Just trying to understand why this happens and if this is something that could happen sometimes? May be one should avoid calling simplify in middle of computation and let the user decide if they want to simplify the final result or not?

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