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Matrix transposition: Difference between revisions
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=={{header|C}}==
Reserving the proper space for the matrix is left to the caller.
<lang c>void transpose_matrix(double *m,
double *d,
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}
}</lang>
Usage example (note that you must specify first the row, then the column):
<lang c>int main()
{
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}
}</lang>
Output:
<pre>
1.00 2.00 3.00 4.00 5.00
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5.00 25.00 125.00 625.00
</pre>
Playing more to
in place with only O(1) space. See the [
<lang c>void▼
▲in place with only O(1) space. See the [http://www.en.wikipedia.org/wiki/In-place_matrix_transposition Wikipedia article]
<lang C>▼
*transpose_matrix(matrix,rows,cols,item_size)
void *matrix;
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size_t item_size;
{
#define ALIGNMENT 16
char *cursor;
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while (block_size)
{
nadir = 1;
while (nadir + 1 < ents)
{
memcpy(carry,&(cursor[(lag = nadir) * item_size]),block_size);
while ((orbit = (lag / rows) + cols * (lag % rows)) > nadir)
{
memcpy(&(cursor[lag * item_size]),&(cursor[orbit * item_size]),block_size);
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memcpy(&(cursor[lag * item_size]),carry,block_size);
orbit = nadir++;
while ((orbit < nadir) ? (nadir + 1 < ents) : 0)
{
orbit = nadir;
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}
return matrix;
No extra storage allocation is required by the caller. Here are
usage examples for an array of doubles and an array of complex numbers.
▲<lang c>
▲b = (complex *) transpose_matrix((void *) b, n, m, sizeof(complex));
After execution, the memory maps of a and b will be those of m by n arrays instead
of n by m.
=={{header|Common Lisp}}==
<lang lisp>(defun transpose (m)
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