# solve: Solve Symbolic Equations In symengine: Interface to the 'SymEngine' Library

 solve R Documentation

## Solve Symbolic Equations

### Description

Solve system of symbolic equations or solve a polynomial equation. Depending on types of arguments, it supports different modes. See Details and Examples.

### Usage

```solve(a, b, ...)

## S4 method for signature 'DenseMatrix'
solve(a, b, ...)

## S4 method for signature 'VecBasic'
solve(a, b, ...)

## S4 method for signature 'Basic'
solve(a, b, ...)
```

### Arguments

 `a, b` Objects, see details. `...` Not used.

### Details

`solve` is a generic function dispatched on the class of the first argument.

• If `a` is a (square) DenseMatrix, it solves the equation `a %*% x = b` for `x`. (similar to `solve.default()`)

• If `a` is a DenseMatrix and `b` is missing, `b` is taken to be an identity matrix and `solve` will return the inverse of `a`. (similar to `solve.default()`)

• If `a` is a VecBasic, it solves the system of linear equations represented by `a` with regards to symbols represented in `b`.

• If `a` is a Basic, it solves the polynomial equation represented by a with regards to the symbol represented in `b`.

### Value

A `VecBasic` or `DenseMatrix` S4 object.

### Examples

```## Inverse of a symbolic matrix
mat <- Matrix(c("A", "B", "C", "D"), 2)
solve(mat)

## Solve a %*% x == b
a <- Matrix(c("a11", "a21", "a12", "a22"), 2) # a is a 2x2 matrix
b <- Vector("b1", "b2")                       # b is a length 2 vector
solve(a, b)                                   # Solution of x (2x1 matrix)

## Solve the system of linear equations represented by a with regards to
## symbols in b
a <- Vector(~ -2*x + y - 4,  # A system of linear equations
~  3*x + y - 9)
b <- Vector(~x, ~y)          # Symbols to solve (x and y)
solve(a, b)                  # Solution of x and y
```

symengine documentation built on Oct. 23, 2022, 5:06 p.m.