gsDesign 3.6.3

New features

• Implemented conditional error spending functions sfXG1(), sfXG2(), and sfXG3() based on Xi and Gallo (2019). See vignette("ConditionalErrorSpending") for details and reproduced examples from the literature (@keaven, #147. Thanks, @xidongdxi, for comments on vignette).

Improvements

• Enhanced eEvents() with input validation to ensure lambda is not NULL (@keaven, 97f629d).

Testing

• Added independent testing for gsSurvCalendar() (@myeongjong, #144).
• Expanded test coverage for gsBinomialExact() (@menglu2, #143).