Examples /
## ComputationWithNumbersAndUnits## An evaluator for numeric expressions with unitsThis code UnitsPl implements an evaluator for numeric expressions with units. The toplevel predicate is isu/2, here are some examples: % dimension-less computation (like is/2) ?- X isu 3+4. X = 7 % units can be used like constants ?- X isu ft. X = 0.3048 m % computation with simple units ?- X isu 3*m + 4*m. X = 7 m % simple units (with an exponent of 1) can be written in postfix notation ?- X isu 3m + 4m. X = 7 m % mixing units (result is always in SI units) ?- X isu 3m + 4ft. X = 4.2192 m % units with higher exponents (Note: multiply sign in 4*m^2 is required!) ?- X isu 3m * 4*m^2. X = 12 * (m)^3 % How much energy is left after you eat a bar of chocolate, then spend 1 hour on the treadmill? ?- Y isu 600kcal - 1h*200'W'. Y = 1790400.0 'J' % What was the speed of light again? (1 lightyear per year) ?- Y isu 1ly/y. Y = 299792458.0 m/(s) % If you run a 50 Watt fridge for 1 year, and pay $0.2 per kilowatt hour, what will you pay over the year? ?- Y isu 1y*50'W' * 0.2/1000'W'h. Y = 87.66 % What speed do you reach after falling 1 minute in vacuum in earth's gravity? ?- Y isu 9.81*m/s^2 * 1min. Y = 588.6 m/(s) % ... and how much is that in furlongs per day? ?- X isu 588.6*m/s / (fur/d). X = 252798.85468861848 % What volume does the cake have? ?- X isu 3icup + 3tbsp + (1/2)pt + 0.5l. X = 0.0016405 * (m)^3 % What's the resistance of a 60W lightbulb? ?- X isu (230'V')^2 / 60'W'. X = 881.66666666666663 'Ohm' % What current flows through it? ?- X isu 230'V' / 882'Ohm'. X = 0.26077097505668934 'A' % comp.lang.prolog 2013-11-05 ?- X isu 5m, Y isu 10s, Z isu X/Y. X = 5 m Y = 10 s Z = 0.5 m/(s) % Examples from http://futureboy.us/frinkdocs/#SampleCalculations ?- Water isu 1kg/l, X isu 10ft*12ft*8ft * Water / lb. Water = 1000.0 kg / (m)^3 X = 59930.842153098834 ?- Water isu 1kg/l, X isu 2t / (10ft*12ft * Water) / ft. Water = 1000.0 kg / (m)^3 X = 0.58857777869147632 |

Page last modified on November 21, 2013, at 12:16 PM