Date: 2013-07-02T14:38:28+00:00

Actual source code: axis.c
petsc-3.4.2 2013-07-02

      2: #include <../src/sys/classes/draw/utils/axisimpl.h>  /*I   "petscdraw.h"  I*/

      6: /*@
      7:     PetscDrawAxisSetLimits -  Sets the limits (in user coords) of the axis

      9:     Not Collective (ignored on all processors except processor 0 of PetscDrawAxis)

     11:     Input Parameters:
     12: +   axis - the axis
     13: .   xmin,xmax - limits in x
     14: -   ymin,ymax - limits in y

     16:     Options Database:
     17: .   -drawaxis_hold - hold the initial set of axis limits for future plotting

     19:     Level: advanced

     21: .seealso:  PetscDrawAxisSetHoldLimits()

     23: @*/
     24: PetscErrorCode  PetscDrawAxisSetLimits(PetscDrawAxis axis,PetscReal xmin,PetscReal xmax,PetscReal ymin,PetscReal ymax)
     25: {

     29:   if (!axis) return(0);
     30:   if (axis->hold) return(0);
     31:   axis->xlow = xmin;
     32:   axis->xhigh= xmax;
     33:   axis->ylow = ymin;
     34:   axis->yhigh= ymax;

     36:   PetscOptionsHasName(((PetscObject)axis)->prefix,"-drawaxis_hold",&axis->hold);
     37:   return(0);
     38: }

     42: /*@
     43:     PetscDrawAxisGetLimits -  Gets the limits (in user coords) of the axis

     45:     Not Collective (ignored on all processors except processor 0 of PetscDrawAxis)

     47:     Input Parameters:
     48: +   axis - the axis
     49: .   xmin,xmax - limits in x
     50: -   ymin,ymax - limits in y

     52:     Level: advanced

     54: .seealso:  PetscDrawAxisSetLimits()

     56: @*/
     57: PetscErrorCode  PetscDrawAxisGetLimits(PetscDrawAxis axis,PetscReal *xmin,PetscReal *xmax,PetscReal *ymin,PetscReal *ymax)
     58: {
     60:   if (!axis) return(0);
     61:   if (axis->hold) return(0);
     62:   *xmin = axis->xlow;
     63:   *xmax = axis->xhigh;
     64:   *ymin = axis->ylow;
     65:   *ymax = axis->yhigh;
     66:   return(0);
     67: }

     71: /*
     72:    val is the label value.  sep is the separation to the next (or previous)
     73:    label; this is useful in determining how many significant figures to
     74:    keep.
     75:  */
     76: PetscErrorCode PetscADefLabel(PetscReal val,PetscReal sep,char **p)
     77: {
     78:   static char    buf[40];

     82:   /* Find the string */
     83:   if (PetscAbsReal(val)/sep <  1.e-4) {
     84:     buf[0] = '0'; buf[1] = 0;
     85:   } else {
     86:     sprintf(buf,"%0.1e",(double)val);
     87:     PetscStripZerosPlus(buf);
     88:     PetscStripe0(buf);
     89:     PetscStripInitialZero(buf);
     90:     PetscStripAllZeros(buf);
     91:     PetscStripTrailingZeros(buf);
     92:   }
     93:   *p =buf;
     94:   return(0);
     95: }

     99: /* Finds "nice" locations for the ticks */
    100: PetscErrorCode PetscADefTicks(PetscReal low,PetscReal high,int num,int *ntick,PetscReal * tickloc,int maxtick)
    101: {
    103:   int            i,power;
    104:   PetscReal      x = 0.0,base=0.0;

    107:   PetscAGetBase(low,high,num,&base,&power);
    108:   PetscAGetNice(low,base,-1,&x);

    110:   /* Values are of the form j * base */
    111:   /* Find the starting value */
    112:   if (x < low) x += base;

    114:   i = 0;
    115:   while (i < maxtick && x <= high) {
    116:     tickloc[i++] = x;
    117:     x           += base;
    118:   }
    119:   *ntick = i;

    121:   if (i < 2 && num < 10) {
    122:     PetscADefTicks(low,high,num+1,ntick,tickloc,maxtick);
    123:   }
    124:   return(0);
    125: }

    127: #define EPS 1.e-6

    131: PetscErrorCode PetscExp10(PetscReal d,PetscReal *result)
    132: {
    134:   *result = PetscPowReal((PetscReal)10.0,d);
    135:   return(0);
    136: }

    140: PetscErrorCode PetscMod(PetscReal x,PetscReal y,PetscReal *result)
    141: {
    142:   int i;

    145:   if (y == 1) {
    146:     *result = 0.0;
    147:     return(0);
    148:   }
    149:   i = ((int)x) / ((int)y);
    150:   x = x - i * y;
    151:   while (x > y) x -= y;
    152:   *result = x;
    153:   return(0);
    154: }

    158: PetscErrorCode PetscCopysign(PetscReal a,PetscReal b,PetscReal *result)
    159: {
    161:   if (b >= 0) *result = a;
    162:   else        *result = -a;
    163:   return(0);
    164: }

    168: /*
    169:     Given a value "in" and a "base", return a nice value.
    170:     based on "sign", extend up (+1) or down (-1)
    171:  */
    172: PetscErrorCode PetscAGetNice(PetscReal in,PetscReal base,int sign,PetscReal *result)
    173: {
    174:   PetscReal      etmp,s,s2,m;

    178:   PetscCopysign (0.5,(double)sign,&s);
    179:   etmp    = in / base + 0.5 + s;
    180:   PetscCopysign (0.5,etmp,&s);
    181:   PetscCopysign (EPS * etmp,(double)sign,&s2);
    182:   etmp    = etmp - 0.5 + s - s2;
    183:   PetscMod(etmp,1.0,&m);
    184:   etmp    = base * (etmp -  m);
    185:   *result = etmp;
    186:   return(0);
    187: }

    191: PetscErrorCode PetscAGetBase(PetscReal vmin,PetscReal vmax,int num,PetscReal *Base,int *power)
    192: {
    193:   PetscReal        base,ftemp,e10;
    194:   static PetscReal base_try[5] = {10.0,5.0,2.0,1.0,0.5};
    195:   PetscErrorCode   ierr;
    196:   int              i;

    199:   /* labels of the form n * BASE */
    200:   /* get an approximate value for BASE */
    201:   base = (vmax - vmin) / (double)(num + 1);

    203:   /* make it of form   m x 10^power,  m in [1.0, 10) */
    204:   if (base <= 0.0) {
    205:     base = PetscAbsReal(vmin);
    206:     if (base < 1.0) base = 1.0;
    207:   }
    208:   ftemp = log10((1.0 + EPS) * base);
    209:   if (ftemp < 0.0) ftemp -= 1.0;
    210:   *power = (int)ftemp;
    211:   PetscExp10((double)-*power,&e10);
    212:   base   = base * e10;
    213:   if (base < 1.0) base = 1.0;
    214:   /* now reduce it to one of 1, 2, or 5 */
    215:   for (i=1; i<5; i++) {
    216:     if (base >= base_try[i]) {
    217:       PetscExp10((double)*power,&e10);
    218:       base = base_try[i-1] * e10;
    219:       if (i == 1) *power = *power + 1;
    220:       break;
    221:     }
    222:   }
    223:   *Base = base;
    224:   return(0);
    225: }