Le forum de XCAS

Hello, I noticed a small error in documentation for implicitdiff, it concerns the last example, in which pd is defined. The last command of that example should be pd[4,0] and not pd[4,0,0]. I've attached the corrected file below. The correction should also be applied to the last example in tooltip h...

Hello, I have improved the lpsolve command. Many parts of code were rewritten or simplified. Also, there are some new features: 1. When solving (mixed) integer LP using branch&bound, suitable Gomory mixed integer (GMI) cuts are added to each subproblem, which usually makes computation significantly ...

Thanks for the clarification. How does is_zero compare with epsilon as it doesn't get a pointer to context?

Hi again,

what's the difference between 'is_zero' and 'is_exactly_zero' functions? Does the first one return true for numbers small enough? I wonder if I'm using them properly...

Hi,

I noticed that Xcas 1.4.9 (linux64) crashes on (misspelled) command:The culprit is wrongly typed semicolon, which should have been a colon. But a similar typo in other commands, such asdoes not cause a crash.

Yes, that's it. Sorry!

I optimized the process of implicit differentiation somewhat. I changed the definition of impldiff type, now it is a map. During computing terms in derive_diffterms, they are automatically grouped so sorting is not needed. Now implicitdiff command is noticeably more agile, producing tenth order part...

I forgot to mention that documentation for optimization functions is also refined! There are some minor changes and improvements. The new version is enclosed within optimization-fix8.zip.

Thanks for the upgrade! Everything works fine, except that 'extrema' and 'periodic' are not highlighted as other commands. Could the option keywords starting with 'lp_' for 'lpsolve' be highlighted as well? I've worked on the code for some more time and I've rewritten some parts used by minimize, ma...

Hi!

The output from 'lvar' may sometimes be counterintuitive (or there is simply a bug). For example, the commandreturns [exp(x),exp(1)]. According to the help index, 'lvar' returns a list of variables with rational dependence, but the second element is a real constant...

There is a bug in function 'solve'. When I enter'solve' returns [-pi/2,pi/2]. But not only these points are excluded from domain of x, but the expression 1/(1+tan(x)^2) can't vanish because it's undefined for x=k*pi/2, where k is integer.

Thank you, i have mirrored this in my version of code. g++ wasn't complaining, so I missed it...

Yes, it probably will... I have simplified the test. Since there is at most one singularity between two consecutive x-points (say x1 and x2) in most cases (actually I've never seen a counterexample, but I'm not sure that it does not exist), I weakened the test a bit: now it checks only the sign of i...

I fixed couple of bugs. 1. The function '_minimize' was returning some meaningless results in cases when 'location' was not given because of applying '_feuille' at the end. 2. Functions 'minimize', 'maximize' and 'extrema' must make some assumptions in certain cases, namely when the variables are en...

Forgot to add lines 1790-1792 in optimization.cc. Just replace the file in fix4 with this one.