The phrase "a complex task in" is correct and usable in written English.
It can be used when describing a challenging or intricate task within a specific field or context.
Example: "Developing a new software application is a complex task in the realm of technology."
Alternatives: "a challenging task in" or "an intricate task in".
Locating power and mapping influence with real precision is a complex task in relatively open societies like Britain's, and this article provides just a snapshot.
b)The Inquiry was faced with a complex task in order to determine whether corruption and collusion, racism or institutional lethargy had (alone or in combination) been causative of the seriously flawed initial investigation of the murder.
Furthermore, fair allocation is still a complex task in distributed systems.
Keeping track of the tangled web of claims and counter claims is becoming a complex task in itself.
The BBC's Tim Vickery in Rio says flushing out the heavily armed drug dealers is a complex task in a densely populated area, but that so far they have encountered less resistance than expected.
However, designing fault tolerance is a complex task in part due to the large scale of integration of SoC systems and different levels of abstraction provided by modern system design languages such as SystemC.
AMC is a complex task especially in a non co-operative environment as in high frequency (HF) communications, where transmission is affected by atmospheric conditions and other transmission interferences [4].
Eradicating global poverty is a complex task, particularly in the politically messy environments of the developing world.
Diet is related to the prevention of chronic diseases, but assessing dietary intake is a complex task, especially in socially vulnerable populations.
Although much of these data are accessible online, their integration is inherently a complex task, and, in most cases, is not performed fully automatically but through manual interactions [1, 2].
The reflections from the students, the findings from the survey and the evaluation of the students' outputs, suggested that though they enjoyed the activity, it was a challenging and a complex task, which in turn provoked their thoughts, creativity and made them acquired teamwork skills.
