Actual source code: axis.c

petsc-3.5.2 2014-09-08
Report Typos and Errors
  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 = PetscLog10Real((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: }