DADiSP is designed to perform technical data analysis in a spreadsheet like environment. However, unlike a typical business spreadsheet that operates on a table of cells each of which contain single scalar values, a DADiSP Worksheet consists of multiple interrelated windows where each window contains an entire series or multi-column matrix. A window not only stores the data, but also displays the data in several interactive forms, including 2D graphs, XYZ plots, 3D surfaces, images and numeric tables. Like a traditional spreadsheet, the windows are linked such that a change to the data in one window automatically updates all dependent windows both numerically and graphically.[3][4] Users manipulate data primarily through windows. A DADiSP window is normally referred to by the letter "W" followed by a window number, as in "W1". For example, the formula W1: 1..3 assigns the series values {1, 2, 3} to "W1". The formula W2: W1*W1 sets a second window to compute the square of each value in "W1" such that "W2" will contain the series {1, 4, 9}. If the values of "W1" change to {3, 5, 2, 4}, the values of "W2" automatically update to {9, 25, 4, 16}.
Programming language
DADiSP includes a series based programming language called SPL (Series Processing Language)[5] used to implement custom algorithms. SPL has a C/C++ like syntax and is incrementally compiled into intermediate bytecode, which is executed by a virtual machine. SPL supports both standard variables assigned with = and "hot" variables assigned with :=. For example, the statement A = 1..3 assigns the series {1, 2, 3} to the standard variable "A". The square of the values can be assigned with B = A * A. Variable "B" contains the series {1, 4, 9}. If "A" changes, "B" does not change because "B" preserves the values as assigned without regard to the future state of "A". However, the statement A := 1..3 creates a "hot" variable. A hot variable is analogous to a window, except hot variables do not display their data. The assignment B := A * A computes the square of the values of "A" as before, but now if "A" changes, "B" automatically updates. Setting A = {3, 5, 2, 4} causes "B" to automatically update with {9, 25, 4, 16}.
History
DADiSP was originally developed in the early 1980s, as part of a research project at MIT to explore the aerodynamics of Formula One racing cars.[4] The original goal of the project was to enable researchers to quickly explore data analysis algorithms without the need for traditional programming.