Sievert Integral

The integral

$$\int_0^\theta e^{-x\sec\phi}\,d\phi.$$

References

Abramowitz, M. and Stegun, C. A. (Eds.). ``Sievert Integral.'' §27.4 in Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables, 9th printing. New York: Dover, pp. 1000-1001, 1972.