The phrase "a complex exercise" is correct and usable in written English.
It can be used to describe a task or activity that involves multiple steps or requires significant thought and effort to complete.
Example: "The final project was a complex exercise that challenged the students to apply their knowledge in innovative ways."
Alternatives: "a challenging task" or "a difficult activity".
While this is without doubt a complex exercise, control theory provides the very tools we require to handle this complexity tractably.
It is a complex exercise.
He added in the report: "I regard the Royal Mail privatisation to have been a complex exercise executed with considerable professionalism.
Big-volume automakers know, then, that choosing a car is a complex exercise influenced by regional culture and national pride, and by more fundamental local issues like road space, tariff and trade barriers, taxes, currency exchange rates and household income.
Questions hang heavy in the air about the now-slimline Whitehall's capacity to carry out such a complex exercise and to succeed where a series of well-resourced inquiries over the past two decades, up to and including a royal commission, has failed to deliver a solution.
Modelling of flood is a complex exercise where a lot of factors are supposed to be considered.
By building a cloud-based planning app, Anaplan has reduced the complexity of what was once a highly complex exercise.
Even if calculating the economic cost of NEETs is a very complex exercise, the Eurofound researchers (Eurofound 2012a), through appropriate simulations, estimated a very high cost.
Meanwhile, the well-trailed news that the government would consult on merging income tax and national insurance contributions as part of a push to simplify the tax system was welcomed by many commentators, although some warned this would be a massively complex exercise.
But if it is a mere technicality to be overcome by clever legal manipulation, then constitutional interpretation is a more complex exercise than the simpleminded reading of the text -- or dubious historical forays into recapturing the intentions of the founding fathers -- favored by two Supreme Court justices whom Mr. Bush says he admires: Antonin Scalia and Clarence Thomas.
