Hi,

I've became an addicted of the Maxima Solve() function, but I am finding some trouble handling cases where one variable has multiple solutions.

Let's say for example that my expression is defined as "x^2-1=0"; the Solve() function will return the correct two solutions for "x" (-1, +1), but they are in boolean format and of not use without an assignment.

Normally I would use the Assign() function to extract and assign the values to the variables, but since the variable name is the same for both solutions, I end up with only one value for "x=+1": I suspect that the Assign function simply loops across the element of the list of solutions and the "x" is overwritten each times, this only the last value on the list is returned.

I know I can access the system of solution returned by the Solve() function by index, but I would like to be able to programmatically save all solutions, or filter down to the valid solution based on a criteria that fit the problem (e.g. I just want positive value for x, or within certain boundary).

I thought I could insert boundary condition (e.g. "x>0" in the system of equations to feed to the Solve() function, but it is not accepted as proper input

I have devised a for-loop to extract all the solutions and convert them to a list (vector) and even filter to just the one I need, but to me it seems a little convoluted for such a common problem that ought to be a better solutions.

filter maxima solve solution.sm (23kb) downloaded 30 time(s).
filter maxima solve solution.pdf (127kb) downloaded 21 time(s).

Lastly, I am aware of the bulit-in solve() function, which will return a vector of solutions, and where I can define the boundary where to find the solution, but I know it does it numerically and will not work if I have some undefined variables (e.g. "x^2-a". Maybe the maple solve could work if expect only one variable (because solutions are not ordered), but I would like to stick with Maxima.

Is there a better way?

EDIT: attached pdf version

Edited by user 16 October 2021 17:26:56(UTC)  | Reason: Not specified

... here is a typical seeded roots scanner.
You can spline for in-situ calculation.

Solve Inverse [Seeded Scanner_roots].sm (17kb) downloaded 14 time(s).

AV Anti Virus
It may be my Win 7 not recognizing your Win 10.
Promised *.PDF missing.

Hi. You can try this approach.

filter maxima solve solution - choose.sm (9kb) downloaded 23 time(s).



Best regards.
Alvaro.

Gotcha. Haven't thought about font shenanigans!

Thanks! Very interesting use of the at() function, I didn't know it could be used with Boolean also. I not fully understand what the line() does to Solve(), but I tried without and and seen for myself that it will not work without.
..................
the line is local definition.
sols:=]for the double vertical ▄
back space on the 2nd one
in the active ▄ solve(x^2-9,x)
More down the document is of local definition style.

Hi. line( ) does the same as defining sols (u) = Solve (eq, u)



filter maxima solve solution - line.sm (12kb) downloaded 13 time(s).

Best regards.
Alvaro.

Edited by user 18 October 2021 19:53:40(UTC)  | Reason: Not specified