string_format

This is a way to format strings, such as decimal numbers and such. Use the syntax for sprintf() for the formatting.

This modifier uses Javascript port of PHP function sprintf(). You can find one at phpjs.org

Parameter Position	Type	Required	Default	Description
1	string	Yes	n/a	This is what format to use. (sprintf)

Template:

{$articleTitle = 23.5787446}

{$number}
{$number|string_format:"%.2f"}
{$number|string_format:"%d"}

output:

23.5787446
23.58
23

see also string_format in PHP Smarty documentation