LaTeX symbol for variations in calculus of variations

[binbagsss]

The functional one used for variations in calculus of variations.
Had a google, can't seem to find.

Thanks a lot.

 

[OldEngr63]

A variation is usually denoted with the lower case Greek delta, δ. This particular font used at PF is somewhat stylized, and looks a bit odd, but I doubt that anyone will misunderstand what is intended.

 

[robphy]

FYI... Great tool: http://detexify.kirelabs.org/classify.html