BASIC vs NewtonianMechanics

BASIC: THE FEELING OF THE GOOD OLD TIMES ! 10 INPUT A 20 B = SIN(A) 30 PRINT "ANSWER: ", B 40 END BASIC USER'S GUIDE: • PRINT 10 PRINT "HELLO WORLD !" 20 END • INPUT 10 INPUT “A=”, A 20 PRINT A 30 END • IF...THEN... Number Comparison: 10 INPUT A 20 IF A＞90 THEN B=“A” 30 PRINT B 40 END Conditional Operators: ＞ greater than ＜ less than ＞= greater than or equal to =＞ equal to or greater than ＜= less than or equal to =＜ equal to or less than = equal to == equal to ＜＞ not equal to != not equal to THEN can be followed by GOTO, GOSUB, INPUT, PRINT. String Comparison: 10 INPUT A 20 IF A=“TOM” THEN PRINT “BOY” 30 END Conditional Operators: = is == is ＜＞ is not != is not • FOR...NEXT... 10 FOR I=1 TO 4 STEP 2 20 PRINT “HELLO”, I 30 NEXT I 40 END STEP specifies the counter increment for each loop. If STEP doesn’t exit, the default increment is 1. FOR...NEXT... loop can be nested. 10 FOR I=1 TO 5 20 FOR J=1 TO 4 30 PRINT I, J 40 NEXT J 50 NEXT I 60 END • GOTO 10 ... 20 ... 30 ... 40 GOTO 10 50 ... • GOSUB 10 PRINT “H” 20 GOSUB 100 30 PRINT “L” 40 END 100 PRINT “A” 110 RETURN • SOUND 10 SOUND C, M, 0.5 The line 10 plays Middle C piano note for 0.5 seconds. Note: C, C#, D, D#, E, F, F#, G, G#, A, A#, B Pitch Range: L (low), M (middle), H (high) Lasting Time: specifies how long a note lasts. C, D, E, F, G, A, B can also be labeled as 1, 2, 3, 4, 5, 6, 7. (C# as 1#). • TEXT 10 TEXT “HELLO”, x, y, size (x,y): position of the string “HELLO”. • CIRCLE 10 CIRCLE x, y, radius (x,y): the center of the circle. • RECTANGLE 10 RECT x, y, width, height (x,y): top-left point of the rectangle. • LINE 10 LINE x1, y1, x2, y2 (x1,y1): the starting point of the line. (x2,y2): the ending point of the line. • POINT 10 POINT x, y (x,y): the position of the point. • CLR: clear the edit window. • CLS: clear the graph window. • DELAY 10 DELAY 0.5 0.5:lasting time in seconds This function is used to suspend execution of a program for a particular time. • CURVE 10 CURVE x, y, radius, 0, PI 0: starting angle PI: ending angle The curve draws clockwise with center (x,y). • Mathematical Functions: SIN(X), COS(X), TAN(X), COT(X), ASIN(X), ACOS(X), ATAN(X), SINH(X), COSH(X), TANH(X), ASINH(X), ACOSH(X), ATANH(X). SQR(X): square root of x. ABS(X): absolute value of x. FCT(X): x factorial. LOG(X): natural logarithm of x. LOG10(X): base-10 logarithm of x. LOG2(X) :base-2 logarithm of x. EXP(X): base-e exponential of x. ERF(X): the error function of x. ERFC(X): the complementary error function of x. ROUND(X) :integral nearest to x. CEIL(X): the smallest integral that is not less than x. FLOOR(X): the largest integral that is not greater than x. TGAMMA(X): the gamma function of x. LGAMMA(X): the natural logarithm of the absolute value of the gamma function of x. • Reserved Variables: INKEY : once a key is pressed, the value of INKEY changes. RND : a random number. PI : π • Some Tips: 1. Undo & Redo typing on iPhone with a shake. 2. Copy an Emoji or some character from other places (like Notes), then paste them on the edit window. 3. Exponentiation is expressed as X^Y.

This is a 3D simulator of Newtonian mechanics. According to the equations of motion and the universal law of gravitation, you set the attributes of a celestial body such as mass, radius, position, and velocity, and the subsequent motion of the body is simulated. Samples are provided for immediate simulation. The samples include Sun and Earth,Black Holes and Small Bodies, GPS, and Geostationary Satellites. Samples can also be modified and saved. This means that users can create new celestial mechanics shows. In the home window, select your favorite sample and press Universe.