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3.2 Mathematical Constants
Constants are represented as functions with no arguments and must be called as such. For instance, the mathematical constant \(\pi\) must be written in a Stan program as pi().
real pi()
\(\pi\), the ratio of a circle’s circumference to its diameter
real e()
\(e\), the base of the natural logarithm
real sqrt2()
The square root of 2
real log2()
The natural logarithm of 2
real log10()
The natural logarithm of 10