How to represent multiple related signals via mathematical function? I have three data sets from same source. I know they are interdependent and stochastic also. The datasets are of very high frequency (see the graph, X axis is time and Y axis is value). I want to represent these three signals in a single mathematical function. Is it possible? 


In the above graph, please see there is a pattern or seasonality. If we change one then other also changes. I have tried to google for it but did not find any model that can completely represent this type of data in a single expression.
Try the Eureqa software. It tries to find the simplest mathematical relation between multiple data. If the relation truly has a simple symbolic form, I think it should find it. Otherwise it will produce some strangely formulated approximation.