Le forum de XCAS

I don't understand this:

solve([a+b=6, a/b=1/2], a) returns []
solve([a+b=6, a/b=1/2], [a]) returns []
solve([a+b=6, a/b=1/2], [a,b]) returns [[2,4]] (correctly)

Is this a bug?

(Is this somehow related to solve([2*x=2,x=1.0], x) ?)

(A year has passed.) An update: I've upgraded to Ubuntu 20.04, and installed xcas 1.5.0 (using Ubuntu's official package manager). The problem has returned: 'xcas' steals the focus. Highly annoying . I found two solutions: (1) Before switching to some other app, save the session. (2) Before switchin...

solve([2*x=2,x=1.0], [x]) returns [[1.0]].
solve([2*x=2,x=1.0], x) returns [].

Is this a bug?

(I know I can write "1" instead of "1.0", and then I get the solution in either case. My "complaint" here is about having to write "[x]" instead of "x".)

Aaahhh.....

I think I understand why xcas displays [[1,2,3]] the way it does: it's a matrix. One that happens to have a single row.

Still, it's problematic that we can't tell the difference between [1,2,3] and [[1,2,3]].

Is there a hidden configuration option to "fix" this?

I've found the problem:

solve() returns a list of lists. So I have to use 'solution[0]', not 'solution'.

I wasn't aware of this because xcas displays this:

[[1,2,3]]

the same as this:

[1,2,3]

So I had no way of knowing there was a list inside

That's a big problem.

Why does xcas do this?

I have a solution to some problem: solution := [z-4, 25-2*z, z] And I'm trying to see what happens when 'z' runs from 0 to 9, so I do: makelist(x->subst(solution, [z=x]), 0, 9) This works ok. 'xcas' displays the big list as a nice matrix which is easy to read. The problem is that in reality my 'solu...

I did this by using the following: I modified runxcas.en to: Thanks. I considered this solution, but it's flawed for me: I usually launch xcas from the directory I work in, as I want xcas to save the file to the diretcory I'm in, without me navigating there. But if I load it with a template file, i...

I suspect I understand why. It's because "x=1" (the solution I was expecting) isn't a solution to the set of equations. In other words, it's as if giac does "subst(equation_set, solution)" and if not *all* the equations in equation_set evaluate to 'true', it's not considered a solution. E.g., "subst...

Hello!

The following works:
But when I do:
I don't get any solution. Why is that?

Just follow the hint: replace ^ by .^ like (pointB - pointA).^2 Given the vector [a,b,c], I want to arrive at a^2 + b^2 + c^2. [a,b,c]^2 does this (but gives a warning). [a,b,c].^2 gives [a^2, b^2, c^2]. Not good. I know I can do "[a,b,c]*[a,b,c]" or "sum([a,b,c].^2)", but I was wondering if there'...

I often need to "dot product" a vector with itself. E.g., "(pointB - pointA)^2". But when I do this I see the warning: Warning, ^ is ambiguous on non square matrices. Use .^ to apply ^ element by element. Is there a way to get rid of this warning? I know I can do "dot(expr, expr)" instead, but then ...

Thanks: I upgraded to 1.5.0 and the problem is gone.

I'm using xcas 1.2.3 (of Ubuntu 18.04). xcas has an autosave feature: every minute, or so, it saves the session (if changes exist in it), to "~/xcas_auto_XXXXXXXX.xws". Unfortunately, this seemingly nice feature makes life unbearable for Linux users: After autosaving, xcas moves the focus to its win...

Thanks for replying. I checked your solution. It works for 'giac' only (the console app), not for 'xcas' (the GUI app). For example, I added ";myfunc(x):=x*666;" to ~/.xcasrc. 'giac' then recognizes "myfunc", but 'xcas' doesn't. Is there a solution that works for 'xcas' as well? For reference, here'...

Is it possible to define my own functions in some file, and have it loaded automatically each time 'giac' or 'xcas' start?