Seite - 2 - in Programming for Computations – Python - A Gentle Introduction to Numerical Simulations with Python

2 1 TheFirstFewSteps maywant to analyze these data inExcel andmake somegraphics out of it. How- ever,assumethereisnomenuinExcel thatallowsyouto importdata in thisspecific format. Excelcanworkwithmanydifferentdataformats,butnot thisone.Youstart searching for alternatives toExcel that can do the same and read this type of data files. Maybe you cannot find any ready-made program directly applicable. You have reached the pointwhereknowinghow towrite programsonyourownwould beof great help to you! With someprogramming skills, youmaywrite your own little programwhichcan translate onedata format to another.With that little piece of tailoredcode,yourdatamaybe readandanalyzed,perhaps inExcel, orperhaps byanewprogramtailored to thecomputations that themeasurementdatademand. The real power of computers can only be utilized if you can program them. By programmingyou can get the computer to do (most often!) exactlywhat you want. Programming consists ofwriting a set of instructions in a very specialized language that has adoptedwords and expressions fromEnglish. Such languages areknownasprogrammingorcomputer languages. Thesetof instructions isgiven to a programwhich can translate themeaning of the instructions into real actions inside thecomputer. Thepurposeof this book is to teach you towrite such instructions dedicated to solvemathematicalandengineeringproblemsbyfundamentalnumericalmethods. There are numerous computer languages for different purposes. Within the en- gineering area, themost widely used computer languages are Python,MATLAB, Octave, Fortran, C, C++, and to some extentMaple, andMathematica. Howyou write the instructions (i.e. the syntax) differsbetween the languages. Let ususe an analogy. Assume youare an international kind of person, having friends abroad inEng- land, Russia andChina. Theywant to try your favorite cake. What can you do? Well, youmaywrite down the recipe in those three languagesand send themover. Now, if you have been able to think correctlywhenwriting down the recipe, and youhavewritten the explanationsaccording to the rules in each language, eachof your friendswill produce the same cake. Your recipe is the “computer program”, whileEnglish,Russian andChinese represent the “computer languages”with their own rules of how towrite things. The endproduct, though, is still the same cake. Note thatyoumayunintentionally introduceerrors inyour“recipe”.Dependingon theerror, thismaycause“bakingexecution” to stop,orperhapsproduce thewrong cake. In your computer program, the errors you introduce are called bugs (yes, small insects! .. . for historical reasons), and the process of fixing them is called debugging. When you try to run your program that contains errors, you usually getwarningsor errormessages. However, the responseyougetdependson the er- ror and theprogramming language. Youmayevenget no response, but simply the wrong“cake”. Note that the rulesof aprogramming languagehave tobe followed verystrictly. ThisdiffersfromlanguageslikeEnglishetc.,wherethemeaningmight beunderstoodevenwith spellingerrorsand“slang” included. Thisbookcomes in twoversions,one that isbasedonPython,andonebasedon Matlab. Both Python andMatlab represent excellent programming environments forscientificandengineeringtasks. Theversionyouare readingnow, is thePython version. Some of Python’s strong properties deservemention here: Many global func- tions can be placed in only onefile, functions are straightforwardly transferred as