ref: 826769af8a3fd2c2f7ba5347f2c7a384c6bb1cd5
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.);
}