Given `L`

and `U`

LU decomposition and vector of constants `b`

such that `LU*x=b`

, is there any built in function which find the `x`

? Mean something like –

```
X = functionName(L,U,b)
```

Note that in both `L`

and `U`

we are dealing with triangular matrices which can be solved directly by forward and backward substitution without using the Gaussian elimination process.

**Edit :**

Solving this linear equation system should be according to the following steps –

```
1. define y - s.t Ux=y
2. solve Ly=b by forward substitution
3. solve Ux=y by backward substitution
4. return y
```

**Edit 2 :**

I found linalg::matlinsolveLU but I didn't try it cause I have too old version (`R2010a`

) . Is it working for anyone ?

## Best Solution

If you have:

then the solution to the system can be simply computed as:

Or if you already have an LU decomposition of A, then:

the

`mldivide`

function is smart enough to detect that the matrix is triangular and chose an algorithm accordingly (forward/backward substitution)