asc-community/angourimath

New open-source cross-platform symbolic algebra library for C# and F#. Can be used for both production and research purposes.

angourimath's Issues

Solve result of (x^2-1)^2-2 is wrong

Also true for (x^2-1)^2-a where a > 2.

Add AngouriMath.Core.Number.TryParse

Support the equality symbol and inequalities

Currently, equations cannot be entities. Inputs like x+y=z, x+y<z and x+y≤z should be supported.

AngouriMath.MathS.Utils.GetUniqueVariables should return a HashSet<VariableEntity>

This is needed by e.g. Derive and SolveEquations. Currently, returning a Set implies that intervals can be returned.

Use C# 8 nullable reference types

Reference https://github.com/manuelroemer/Nullable.

What about the sets N, Z and Q?

Cannot get 9+6*x+x^2 from (x+3)^2

Expand: x*x+x*3+3*x+3*3
Expand+Simplify: 9+(6+x)*x

Why include a closed-source component in an open source solution?

I'm talking about the Interactive folder.

Simplify a / b / c into a / (b * c)

So that the LaTeX output can be \frac{a}{b\times c} instead of \frac{\frac{a}{b}}{c} which takes a lot of vertical space.

Extend EquationSystem solving to eliminate the number of equations = number of variables limitation

e.g. AngouriMath.MathS.Equations("a+b-c", "a-b-c").Solve("a", "b", "c")

1e can be Eval()ed but not e itself

Math constants are not recognized by compile method

Description
trying to compile expression which contains math constants such as e and pi generates exception because Compile method recognizes them as variables:

System.Collections.Generic.KeyNotFoundException: 'The given key 'e' was not present in the dictionary.'

   at System.ThrowHelper.ThrowKeyNotFoundException[T](T key)
   at System.Collections.Generic.Dictionary`2.get_Item(TKey key)
   at AngouriMath.Entity.InnerCompile(FastExpression fe, String[] variables, Dictionary`2 varNamespace) in C:\Users\Momo\source\repos\MathS\AngouriMath\Functions\Evaluation\Compilation\FastExpression.cs:line 106
   at AngouriMath.Entity.InnerCompile(FastExpression fe, String[] variables, Dictionary`2 varNamespace) in C:\Users\Momo\source\repos\MathS\AngouriMath\Functions\Evaluation\Compilation\FastExpression.cs:line 100
   at AngouriMath.Entity.Compile(String[] variables) in C:\Users\Momo\source\repos\MathS\AngouriMath\Functions\Evaluation\Compilation\FastExpression.cs:line 48
   at Samples.Program.Main(String[] _) in C:\Users\Momo\source\repos\MathS\Samples\Samples\Program.cs:line 139

(see https://github.com/Angourisoft/MathS/blob/master/AngouriMath/Functions/Evaluation/Compilation/FastExpression.cs#L106)

To Reproduce

static void Main(string[] args)
{
    AngouriMath.Entity expr = "x - pi";
    expr.Compile("x");
}

Conditions
AngouriMath 1.0.17.2-Beta (latest)
Visual Studio 2019
Possible solution
Probably we need to replace such constants with their numeric alternatives if variables with the same names were not passed to the compile method.

Order polynomials from highest degree to lowest degree after simplifying

Naming conflict

Hi,

Just noticed you seem to have the exact same name as my repo, https://github.com/john-h-k/MathSharp. This could potentially be an issue for both of us?

Limits

Add limits

Add a way to collect intermediate pattern replacements when simplifying

Add a way to collect intermediate pattern replacements when simplifying.
e.g.
Input: x^(-1)/(y/z)
Output[0]: x^(-1)*z/y // any1 / (any2 / any3) -> any1 * any3 / any2
Output[1]: 1/x*z/y // Powf.PHang(any1, Num(-1)) -> 1 / any1
...

Add periodic roots for complex exponent solver

Solving following equation returning only one solution:

var expr = MathS.FromString("e^(i*x) - 0.5");
var sol = MathS.SolveEquation(expr, "x");

But actually this equation has inifinite number of periodic roots (example from WolframAlpha):
https://www.wolframalpha.com/input/?i=e%5Eix+%3D+0.5

Add a way to solve for all variables in an equation or an equation system

Currently only solving for one variable is supported.

Infinite loop while solving equation

Description
trying to solve expression for variable which does not exists, causes Solve method to execute forever. This happens because of infitine while loop in AnalyticalSolver:
https://github.com/Angourisoft/MathS/blob/master/AngouriMath/Functions/Algebra/AnalyticalSolver/AnalyticalSolver.cs#L61

To Reproduce

static void Main(string[] args)
{
    AngouriMath.Entity expr = "1";
    expr.Solve("x");
}

Conditions
AngouriMath 1.0.17.2-Beta (latest)
Visual Studio 2019
Possible solution
if we find Entity with no children and it is not our entity - we should break from loop. Consider checking latest commit to MomoBranch: d87422c

a / b -> a * b ^ (-1) simplification is inconsistent

Describe the bug

a + b / c Simplify-> a + b / c
a - b / c Simplify-> a - b * c ^(-1)
a * b / c Simplify-> a * b / c
a / b / c Simplify-> a * b ^ (-1) / c

Conditions
latest master

Use formulae such as the binomial theorem and its generalisations to expand an entity

What is "This function is every interesting for ASC (https://asc-community.org)"?

https://github.com/asc-community/MathS/blob/f8ca3cc39442fabef18e6a8da0c306729ef01294/AngouriMath/Convenience/MathS.cs#L107-L123

Support min, max, mean, mode, median

With symbolic results.

Sets should be Entities

Sets should support operations on entities, such as arithmetic and functions.

x^4*x^y-1 unsolvable for x but x^(4+y)-1 is solvable

Check if n is already used when solving for multiple solutions

For example, Wolfram Alpha uses c_1 instead when n is present.

Solution is incomplete. There is no way to get cos(x)^2+2*cos(x)+1 from (cos(x)+1)^2.

#61 (comment)

Keep irrational numbers and fractions until Eval is called

So that symbolic computation, e.g. log(5, 3) + log(25, 3) Simplify-> 3 * log(5, 3) can be supported.

Website address is unreachable

Describe the bug
https://asc-community.org

To Reproduce
Open the link

Conditions
Use a browser

Rename EntitySet -> EntityList

Set implies unorderedness.

Add secant and cosecant

I want to contact with you

I am impressed with this project so can you give me your email to contact? I want to ask you something

Implement solving for log(2, x)=6

solving pi-1^x results in hang

x^2+y^2+2x*y+w -> w+x^2+2x*y+y^2

#62 (comment)

TryPolynomial is not able to support multiple variables though. I said
There is already a sort performed by Simplify which sorts variables according to their alphabetical order. On top of this, we should follow the mathematical norm of writing higher powers of the same variable first.
So on top of y^2+x^2->x^2+y^2 we would also have x+x^2->x^2+x.
So multiple variables like x^2+y^2+2xy+w would first sort by w, then x, finally y: w+x^2+2xy+y^2

In addition, functions like cos(x) can also follow the alphabetical order of cos.

(x^2+2x*y+y^2)/(x+y) Simplify-> x+y but (x^2+2x*y+y^2)/(x^2-y^2) Simplify-> (x^2+2x*y+y^2)/(x-y)/(x+y)

Works correctly for (x^2-2x*y+y^2)/(x^2-y^2) though.

LaTeXising a Set

Why .NET Standard 2.1?

From NuGet, this used to target .NET Standard 2.0. Why was this changed? .NET Standard 2.1 is not supported on multiple platforms such as .NET Framework and UWP which harms adoption of this library. As far as I can see, there is nothing added in .NET Standard 2.1 that is explicitly used by this library. It would be better to switch back.

a/b+2 throws when Simplify()ed

MathS.Solve("x^(1y)-3", "y").Count is 1 but MathS.Solve("x^y-3", "y").Count is 0

Either expose IsTensoric() or make CrossProduct and DotProduct accept Entities

Currently there is no way to properly support the × symbol and the · symbol on arbitrary entities.

((x^2-2)^2-y)^3 Expand-> Simplify-> [A lot of (-8)*x^6 that do not get simplified]

Differentiation etc. as Entities

Differentiation can appear inside other math operations in normal mathematics. This should be supported.

Solving x^3+6-sqrt(x)(x-3) hangs

Support factorials and the gamma function

Collapse cannot factorize x^2-1

Simplification given a variable is in a set

e.g. Given x >= 0, we can simplify sqrt(x^2) to x, and -x given x < 0.

What?

Describe the bug

AngouriMath.MathS.Equations("a+b-c", "3a+3b-2c", "3a+4b-4c").Solve("a", "b", "c").Latexise()

\begin{pmatrix}NaN + NaNi & -NaN + NaNi & NaN + NaNi+-NaN + NaNi\end{pmatrix}

LaTeXize pi to \pi

Keep track of #33

Enable _ to imitate variables with subscripts

Keep track of #39