Page - 31 - in Programming for Computations – Python - A Gentle Introduction to Numerical Simulations with Python 3.6, Volume Second Edition

1.6 Plotting,PrintingandInputData 31 dt = 0.55 t = t0 + 0*dt; g = t*sin(t) print(’{:6.2f} {:8.3f}’.format(t, g)) t = t0 + 1*dt; g = t*sin(t) print(’{:6.2f} {:8.3f}’.format(t, g)) t = t0 + 2*dt; g = t*sin(t) print(’{:6.2f} {:8.3f}’.format(t, g)) Running thisprogram,we get theprintout 2.00 1.819 2.55 1.422 3.10 0.129 Observe that the columns are nicely aligned here. With the formatting, we effec- tively control the width of each column and also the number of decimals. The numbers in each column will then become nicely aligned under each other and writtenwith thesameprecision. To the contrary, if we had skipped the detailed formatting, and rather used a simplercall toprint like print(t, g) thecolumnswouldbe printedas 2.0 1.81859485365 2.55 1.42209347935 3.1 0.128900053543 Observe that theniceandeasy-to-readstructureof theprintoutnowisgone. 1.6.3 Printing:Thef-String We should briefly also mention printing by use of f-strings. Above, we printed the valuesofvariablesv1andv2,being10.0and20.0, respectively.Oneof thecallswe used toprintwas (repeatedhere foreasy reference) print(’v1 is {} \nv2 is {}’.format(v1, v2)) # \n gives new line and it producedtheoutput v1 is 10.0 v2 is 20.0 However, if we rather skip.format(v1, v2), and instead introduceanf in front of the string, we can produce the very same outputby the followingsimpler call to print: print(f’v1 is {v1} \nv2 is {v2}’) So, f-strings21 are quitehandy! 21 Read more about f-strings athttps://www.python.org/dev/peps/pep-0498.