Differences between expression based languages and block structured languages


Frame out the differences between expression based languages and block structured languages and for which type of systems both the languages will be used?
Ans: BLOCK STRUCTURED LANGUAGES:  A block-structured control system is a coupling of functional blocks. Each of these functional blocks stands for a subsystem in the original system. In control systems, a functional block can be classified into two categories: linear and nonlinear. In a block-structured programming language, the names of variables and other objects such as procedures which are declared in outer blocks are visible inside other inner blocks, unless they are shadowed by an object of the same name.
EXPRESSION ORIENTED CONTINUOUS LANGUAGES: are based on writing expressions that represent the mathematical model. So the system simulated must be expressed by a set of equations. Then the user adds statements and/or directives that control the simulation. Some languages enable both block and expression based ways of system definition. Simulation control means selection of: the integration method because some languages offer more, the integration step, the variables outputs of blocks that should be observed, the intervals for collecting data for printing and/or plotting, scaling of outputs that may be also done automatically, duration of the simulation runs, number of repetitions and the way certain values are changed in them, etc.

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