/* Sets the edges of the viewport to the specified normalized subpage */
/* coordinates */

#include "plplot.h"

void plvpor(xmin, xmax, ymin, ymax)
float xmin, xmax, ymin, ymax;
{
    float spdxmi, spdxma, spdymi, spdyma;
    float vpdxmi, vpdxma, vpdymi, vpdyma;
    int vppxmi, vppxma, vppymi, vppyma;
    
    int nx, ny, cs;

    int level;

    glev(&level);
    if (level < 1) fatal("Please call PLSTAR before calling PLVPOR.");
    if((xmin>=xmax)||(ymin>=ymax)||(xmin<0.)||
       (ymin<0.)||(xmax>1.)||(ymax>1.))
        fatal("Invalid limits in PLSVPA.");

    gsub(&nx,&ny,&cs);
    if ((cs<=0) || (cs>(nx*ny)))
        fatal("Please call PLADV or PLENV to go to a subpage.");
    gspd(&spdxmi,&spdxma,&spdymi,&spdyma);
    vpdxmi = spdxmi + (spdxma - spdxmi) * xmin;
    vpdxma = spdxmi + (spdxma - spdxmi) * xmax;
    vpdymi = spdymi + (spdyma - spdymi) * ymin;
    vpdyma = spdymi + (spdyma - spdymi) * ymax;
    svpd(vpdxmi,vpdxma,vpdymi,vpdyma);

    vppxmi = dcpcx(vpdxmi);
    vppxma = dcpcx(vpdxma);
    vppymi = dcpcy(vpdymi);
    vppyma = dcpcy(vpdyma);
    svpp(vppxmi,vppxma,vppymi,vppyma);
    sclp(vppxmi,vppxma,vppymi,vppyma);
    slev(2);
}