Figure 4
The polyxcalc programmable mass calculator. The mass calculator is polymer chemistry definition-aware, and in this figure it is represented pre-loaded with the "protein" polymer chemistry definition (top of the left window). When, upon opening of the calculator, a polymer chemistry definition is loaded, its chemical entities (monomers and chemical modifications, as shown) become available in the calculator's widgets; otherwise only atoms and formulas can be used. The calculator is programmable, and a simple syntax allows the definition of the layout of a "chemical pad" to perform quick chemical calculation tasks in the calculator.