# catalan

Catalan constant

## Description

example

catalan represents the Catalan constant. To get a floating-point approximation with the current precision set by digits, use vpa(catalan).

## Examples

### Approximate Catalan Constant

Find a floating-point approximation of the Catalan constant with the default number of digits and with the 10-digit precision.

Use vpa to approximate the Catalan constant with the default 32-digit precision:

vpa(catalan)
ans =
0.91596559417721901505460351493238

Set the number of digits to 10 and approximate the Catalan constant:

old = digits(10);
vpa(catalan)
ans =
0.9159655942

Restore the default number of digits:

digits(old)

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### Catalan Constant

The Catalan constant is defined as follows:

$\mathrm{catalan}=\sum _{i=0}^{\infty }\frac{{\left(-1\right)}^{i}}{{\left(2\text{ }i+1\right)}^{2}}=\frac{1}{{1}^{2}}-\frac{1}{{3}^{2}}+\frac{1}{{5}^{2}}-\frac{1}{{7}^{2}}+\dots$

## Version History

Introduced in R2014a