git: 9front

ref: a0ba4c1f03a3f99fb17a9edf9b4448db49bb6c46
dir: /sys/src/cmd/plot/libplot/frame.c/

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#include "mplot.h"
void frame(double xs, double ys, double xf, double yf){
	register double	osidex, osidey;
	osidex = e1->sidex;
	osidey = e1->sidey;
	e1->left = e0->left + xs * e0->sidex;
	e1->bottom = e0->bottom + ys * e0->sidey;
	e1->sidex = (xf-xs)*e0->sidex;
	e1->sidey = (yf-ys)*e0->sidey;
	e1->scalex *= (e1->sidex / osidex);
	e1->scaley *= (e1->sidey / osidey);
	e1->quantum=e0->quantum/sqrt(e1->scalex*e1->scalex +
		e1->scaley*e1->scaley);
	if(e1->quantum < .01)
		e1->quantum = .01;
}