FormulaCalculator

class decida.FormulaCalculator.FormulaCalculator(parent=None, par_specs=None, recalc_specs=None, title='')

synopsis:

Simple formula calculator.

A small calculator can be useful to evaluate a single formula involving a few parameters/variables. This formula calculator class constructs a small calculator which evaluates the formula or its inverse with respect to a particular parameter, according to specified code for each result.

(originally posted as a Tcl/Tk application on wiki.tcl.tk)

constructor arguments:

parent (Tkinter handle, default=None)

handle of frame or other widget to pack plot in. if this is not specified, top-level is created.

par_specs (list of lists of parameter specifications)

each list of parameter specifications is: parameter name, text to be displayed for the parameter label in the GUI, units, initial value, key of equation recalculation formula.

recalc_specs (list of lists of formula specifications)

each list of recalculation specifications is: recalculation key, formula.

results:

• Sets up GUI for formula recalculation.
• Changing and typing return in a parameter entry box re-evaluates the respective formula.
• Emacs-style bindings switch between entry boxes: ^n and ^p focus on next or previous entry windows, respectively

example (from test_FormulaCalculator_1):

from decida.FormulaCalculator import FormulaCalculator
fc = FormulaCalculator(None,
    title="L-C oscillator",
    par_specs = [
        ["L",    "Inductance",  "pH", 1000.0, "f"],
        ["C",    "Capacitance", "pF",  25.00, "f"],
        ["freq", "Frequency",   "GHz",  1.00, "L"],
    ],
    recalc_specs = [
        ["f", "freq = 1e3/(2*pi*sqrt(L*C))"],
        ["L", "L    = 1e6/(C*pow(2*pi*freq, 2))"],
        ["C", "C    = 1e6/(L*pow(2*pi*freq, 2))"],
    ]
)

recalculate(par_changed)