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A square identity matrix of size n can be generated using the function eye, and matrices of any size with zeros or ones can be generated with the functions zeros and ones, respectively. >> eye ( 3 , 3 ) ans = 1 0 0 0 1 0 0 0 1 >> zeros ( 2 , 3 ) ans = 0 0 0 0 0 0 >> ones ( 2 , 3 ) ans = 1 1 1 1 1 1
In addition to support for vectorized arithmetic and relational operations, these languages also vectorize common mathematical functions such as sine. For example, if x is an array, then y = sin (x) will result in an array y whose elements are sine of the corresponding elements of the array x. Vectorized index operations are also supported.
In C and C++ arrays do not support the size function, so programmers often have to declare separate variable to hold the size, and pass it to procedures as a separate parameter. Elements of a newly created array may have undefined values (as in C), or may be defined to have a specific "default" value such as 0 or a null pointer (as in Java).
A more efficient implementation would allocate a single array for y, and compute y in a single loop. To optimize this, a C++ compiler would need to: Inline the sin and operator+ function calls. Fuse the loops into a single loop. Remove the unused stores into the temporary arrays (can use a register or stack variable instead).
Function rank is an important concept to array programming languages in general, by analogy to tensor rank in mathematics: functions that operate on data may be classified by the number of dimensions they act on. Ordinary multiplication, for example, is a scalar ranked function because it operates on zero-dimensional data (individual numbers).
2.21 MATLAB. 2.22 Mint. 2.23 Objective-C. ... C int array as a collection of int (array size known at compile-time) ... that applies each element to a function, which ...
As exchanging the indices of an array is the essence of array transposition, an array stored as row-major but read as column-major (or vice versa) will appear transposed. As actually performing this rearrangement in memory is typically an expensive operation, some systems provide options to specify individual matrices as being stored transposed.
The arrays V and COL_INDEX are of length NNZ, and contain the non-zero values and the column indices of those values respectively; COL_INDEX contains the column in which the corresponding entry V is located. The array ROW_INDEX is of length m + 1 and encodes the index in V and COL_INDEX where the given row starts.