Meanings of mathematical functions in English

ECG was processed in order to obtain numerical values, which were analyzed by nonlinear mathematical functions.

Three men sat around a table which was littered with graphs, sketches of mathematical functions, and books of tensor formulae.

Such traditional mathematical functions such as SINE and COSINE, however, were deliberately excluded as being unnecessary to business data processing applications.

The process of developing new test statistics is laborious, requiring the manual development and evaluation of mathematical functions that satisfy several theoretical properties.

Yes I know what it looks like, but it is in fact a complex four-dimensional topographical map of a series of highly complex mathematical functions.