ref: 2ce5f2b4ecfc37cbc032b5ea2102caa2de7bd6c6
dir: /sys/src/cmd/plot/libplot/openpl.c/
#include "mplot.h"
void openpl(char *s){
m_initialize(s);
e0->left=mapminx;
e0->bottom=mapmaxy;
e0->sidex=mapmaxx-mapminx;
e0->sidey=mapminy-mapmaxy;
e0->scalex=e0->sidex;
e0->scaley=e0->sidey;
sscpy(e0, e1);
move(0., 0.);
}