"dsimcha" <dsimcha at yahoo.com> wrote in message news:iocalv$2h58$1 at digitalmars.com... > Output: > Rounding mode: 0 > 0.7853986633972191094 > Rounding mode: 0 > 0.7853986633972437348 Could be something somewhere is getting truncated from real to double, which would mean 12 fewer bits of mantisa. Maybe the FPU is set to lower precision in one of the threads?