<pikhq> ` cat >src/pikhqbow.c <<<$\'#include <stdio.h>\\n#include <wchar.h>\\n\'\'int main(){wint_t c;int a=2;b:c=fgetwc(stdin);if(c==EOF) return 0;printf("\\x03%02d%s%lc",a,c==L\'\\\'\',\'\\\'\'?",99":"",c);a++;if(a==14)a=2;goto b;}\'

Sparse matrix algorithms are a trivial special case of non-sparse matrix algorithms, by conjugating with the sparsification operation.