Unit 10 Computational Thinking

A way of separating the logical and physical aspects of a problem such as removing less relevant parts of a problem

• Clearly documenting preconditions helps to make the function reusable • Cuts out unnecessary checks • Makes the program shorter which helps to speed up debugging and maintenance

• Inputs, outputs and preconditions should be documented • Variable identifiers should conform to a standard convention • All variables must be local to the module • Documentation should be in a standard format, explaining what the module does, who it was written by, date it was written • Explanations of certain sections of code should be included where necessary • No module should exceed one page of code

To make them easy to use for other programmers

Caching is the temporary storage of data and instructions. The last few instructions of a program or frequently used data could be stored

• Faster access to cached resources • Saving on costly use of bandwidth • Reduced load on web services in a client-server environment

Slower performance if the resource isn’t found in the cache

Procedural decomposition means breaking a problem into a number of sub-problems, so that each sub-problem accomplishes an identifiable task

Program structure and organization, i.e. breaking the problem down into subroutines

• Large programs are broken down into subtasks/subroutines that are easier to program and manage • Each subroutine can be individually tested • Modules can be re-used several times in a program • Frequently used modules can be saved in a library and used by other programs • Several programmers can simultaneously work on different modules, shortening development time

• Use meaningful identifiers • Define and document the inputs, outputs and preconditions for each sub-procedure • Add lots of meaningful comments within the program • At the bottom level, each sub-procedure should perform a single task • Keep each sub-procedure self-contained by passing parameters and using local variables

• Has clear and precisely stated steps that produce the correct output for any set of valid inputs • Should allow for invalid inputs • Must always terminate at some point • Should execute efficiently, in as few steps as possible • Should be designed in such a way that other people will be able to understand it and modify it if necessary

• Figuring out how an algorithm works • Finding out why an algorithm is not working properly

Multiple processors execute instructions simultaneously Tasks are broken down into sub-tasks that can be assigned to separate processors to perform simultaneously

The process of designing a model of a real system in order to understand the behaviour of the system, and to evaluate various strategies for its operation