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# double

Convert symbolic matrix to MATLAB numeric form

r = double(S)

## Description

r = double(S) converts the symbolic object S to a numeric object r.

## Input Arguments

 S Symbolic constant, constant expression, or symbolic matrix whose entries are constants or constant expressions.

## Output Arguments

 r If S is a symbolic constant or constant expression, r is a double-precision floating-point number representing the value of S. If S is a symbolic matrix whose entries are constants or constant expressions, r is a matrix of double precision floating-point numbers representing the values of the entries of S.

## Examples

Find the numeric value for the expression $\frac{1+\sqrt{5}}{2}$:

`double(sym('(1+sqrt(5))/2')))`
`1.6180`

Find the numeric value for the entries of this matrix T:

```a = sym(2*sqrt(2));
b = sym((1-sqrt(3))^2);
T = [a, b; a*b, b/a];
double(T)```
```ans =
2.8284    0.5359
1.5157    0.1895```

Find the numeric value for this expression. By default, double uses a new upper limit of 664 digits for the working precision and returns the value 0:

```x = sym('((exp(200) + 1)/(exp(200) - 1)) - 1');
double(x)```
```ans =
0```

To get a more accurate result, increase the precision of computations:

```digits(1000)
double(x)```
```ans =
2.7678e-87```