Charles E. Grant
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 Nov 20 awarded Good Answer Oct 17 comment What are the advantages of matrix multiplication over individual variables (graphics)? Ah! I see what you are getting at now. The trick is that the most general transformation matrix is highly structured. In 2d, the first two columns of the 3rd row will always be 0, which makes many of the normal operations pointless. A general matrix multiplication function won't take advantage of that, but you could write a specialized matrix multiplication function limited to transformation matrices, which would. It's innards would end up looking a lot like the arithmetic in your main(). Oct 17 comment What are the advantages of matrix multiplication over individual variables (graphics)? That may be what's confusing you. The tutorials you were looking at seem to be doing 3d transforms (note the Z coordinate). For 2d transforms your expression is correct, but 2d transforms are described by 2x2 matrixes, so you end up with the same number of arithmetic operations as with your expression. The geometry is the geometry, matrix multiplication is just a concise way to write it. Oct 17 comment What are the advantages of matrix multiplication over individual variables (graphics)? Are you talking about 3d or 2d transformations? Your expression using scale_x, sin_a, etc. only covers scaling, translation, and rotation in a 2-d plane. It's missing a 'z' coordinate. For scaling, translation, and rotation in 3-d you indeed need a 3x3 matrix. Oct 8 awarded Yearling Aug 27 comment Why are C string literals read-only? 'So string literals are stored in program memory, not RAM, and buffer overflow would result in the corruption of program itself?' The program image is in RAM too. To be precise, the string literals are stored in the same segment of RAM used to store the program image. And yes, overwriting the string could corrupt the program. Back in the days of MS-DOS and CP/M there was no memory protection, you could do stuff like this, and it usually caused terrible problems. The first PC viruses would use tricks like that to modify your program so it formatted your hard drive when you tried to run it. Aug 6 comment Are data type declarators like “int” and “char” stored in RAM when a C program executes? @user16307 `Otherwise how can console or text file outputs a character instead of int` Because there is a different sequence of instructions for outputting the contents of a memory location as an integer or as an alphanumeric characters. The compiler does know about the variables types, and chooses the appropriate sequence of instructions at compile time, and records it in the EXE. Jul 26 awarded Guru Jul 25 awarded Good Answer Jul 25 awarded Nice Answer Jul 20 comment rand() gives same numbers again for a small range `Next, rand() is typically a linear congruential generator` This isn't true on many platforms now. From the rand(3) man page of linux:" The versions of rand() and srand() in the Linux C Library use the same random number generator as random(3) and srandom(3), so the lower-order bits should be as random as the higher-order bits." Also, as @delnan points out, the quality of the PRNG isn't the real problem here. Jul 17 answered Why isn't programming mobile apps more similar to programming desktop applications? Jul 10 comment In C, how are functions accessible if they're not inline or called by #include? @Volumetricsteve that's almost certainly the case, but keep in mind that compiling and linking are separate processes in C. If your code is referring to functions or datatypes defined in a different library, those will need to get declared in your program before it will compile. This is almost certainly happening via the include of some header file. Exactly where it's occuring may be obscured by nesting, For example, you include file "foo.h", which in turn includes "bar.h", which includes "png_magic.h", which provides the needed declarations. Jul 10 revised In C, how are functions accessible if they're not inline or called by #include? deleted 36 characters in body Jul 10 answered In C, how are functions accessible if they're not inline or called by #include? Jun 24 awarded Nice Answer Apr 27 comment Is it always a good idea to divide large classes into smaller ones? What do you mean by "too many objects"? Do you have any objective standard for that judgement? Apr 24 comment Why are floating point numbers used often in Science/Engineering? @MichaelGrünewald, What you say is certainly true, but I think primarily of interest to mathematicians and their fellow travelers. The subtext of the original question is that many work-a-day programmers find floating point arithmetic baffling. I suspect this is because they mostly work with computations that can be made with perfect precision using integers from a finite range (think bookkeeping and inventory). Floating point arithmetic is confusing for them because they don't appreciate that they've entered a problem domain where perfect precision is impossible. Apr 24 comment Why are floating point numbers used often in Science/Engineering? @PaulChernoch, sure, but there is a performance cost to that. Nobody is going to re-write their finite element modeling package or their machine learning library to use a continued fraction representation or even arbitrary precision rationals because they can't afford the performance penalty. As I said in my answer, scientific computing is a trade-off among precision, range, and speed. Apr 24 answered Is this a good game plan to become a fluent Java developer?