1 2 #include <petsc/private/drawimpl.h> /*I "petscdraw.h" I*/ 3 4 /* 5 val is the label value. sep is the separation to the next (or previous) 6 label; this is useful in determining how many significant figures to 7 keep. 8 */ 9 PetscErrorCode PetscADefLabel(PetscReal val,PetscReal sep,char **p) 10 { 11 static char buf[40]; 12 13 PetscFunctionBegin; 14 /* Find the string */ 15 if (PetscAbsReal(val)/sep < 1.e-4) { 16 buf[0] = '0'; buf[1] = 0; 17 } else { 18 sprintf(buf,"%0.1e",(double)val); 19 PetscCall(PetscStripZerosPlus(buf)); 20 PetscCall(PetscStripe0(buf)); 21 PetscCall(PetscStripInitialZero(buf)); 22 PetscCall(PetscStripAllZeros(buf)); 23 PetscCall(PetscStripTrailingZeros(buf)); 24 } 25 *p = buf; 26 PetscFunctionReturn(0); 27 } 28 29 /* Finds "nice" locations for the ticks */ 30 PetscErrorCode PetscADefTicks(PetscReal low,PetscReal high,int num,int *ntick,PetscReal *tickloc,int maxtick) 31 { 32 int i,power; 33 PetscReal x = 0.0,base=0.0,eps; 34 35 PetscFunctionBegin; 36 PetscCall(PetscAGetBase(low,high,num,&base,&power)); 37 PetscCall(PetscAGetNice(low,base,-1,&x)); 38 39 /* Values are of the form j * base */ 40 /* Find the starting value */ 41 if (x < low) x += base; 42 43 i = 0; eps = base/10; 44 while (i < maxtick && x <= high+eps) { 45 tickloc[i++] = x; x += base; 46 } 47 *ntick = i; 48 tickloc[i-1] = PetscMin(tickloc[i-1],high); 49 50 if (i < 2 && num < 10) { 51 PetscCall(PetscADefTicks(low,high,num+1,ntick,tickloc,maxtick)); 52 } 53 PetscFunctionReturn(0); 54 } 55 56 #define EPS 1.e-6 57 58 PetscErrorCode PetscExp10(PetscReal d,PetscReal *result) 59 { 60 PetscFunctionBegin; 61 *result = PetscPowReal((PetscReal)10.0,d); 62 PetscFunctionReturn(0); 63 } 64 65 PetscErrorCode PetscMod(PetscReal x,PetscReal y,PetscReal *result) 66 { 67 int i; 68 69 PetscFunctionBegin; 70 if (y == 1) { 71 *result = 0.0; 72 PetscFunctionReturn(0); 73 } 74 i = ((int)x) / ((int)y); 75 x = x - i * y; 76 while (x > y) x -= y; 77 *result = x; 78 PetscFunctionReturn(0); 79 } 80 81 PetscErrorCode PetscCopysign(PetscReal a,PetscReal b,PetscReal *result) 82 { 83 PetscFunctionBegin; 84 if (b >= 0) *result = a; 85 else *result = -a; 86 PetscFunctionReturn(0); 87 } 88 89 /* 90 Given a value "in" and a "base", return a nice value. 91 based on "sign", extend up (+1) or down (-1) 92 */ 93 PetscErrorCode PetscAGetNice(PetscReal in,PetscReal base,int sign,PetscReal *result) 94 { 95 PetscReal etmp,s,s2,m; 96 97 PetscFunctionBegin; 98 PetscCall(PetscCopysign (0.5,(double)sign,&s)); 99 etmp = in / base + 0.5 + s; 100 PetscCall(PetscCopysign (0.5,etmp,&s)); 101 PetscCall(PetscCopysign (EPS * etmp,(double)sign,&s2)); 102 etmp = etmp - 0.5 + s - s2; 103 PetscCall(PetscMod(etmp,1.0,&m)); 104 etmp = base * (etmp - m); 105 *result = etmp; 106 PetscFunctionReturn(0); 107 } 108 109 PetscErrorCode PetscAGetBase(PetscReal vmin,PetscReal vmax,int num,PetscReal *Base,int *power) 110 { 111 PetscReal base,ftemp,e10; 112 static PetscReal base_try[5] = {10.0,5.0,2.0,1.0,0.5}; 113 int i; 114 115 PetscFunctionBegin; 116 /* labels of the form n * BASE */ 117 /* get an approximate value for BASE */ 118 base = (vmax - vmin) / (double)(num + 1); 119 120 /* make it of form m x 10^power, m in [1.0, 10) */ 121 if (base <= 0.0) { 122 base = PetscAbsReal(vmin); 123 if (base < 1.0) base = 1.0; 124 } 125 ftemp = PetscLog10Real((1.0 + EPS) * base); 126 if (ftemp < 0.0) ftemp -= 1.0; 127 *power = (int)ftemp; 128 PetscCall(PetscExp10((double)-*power,&e10)); 129 base = base * e10; 130 if (base < 1.0) base = 1.0; 131 /* now reduce it to one of 1, 2, or 5 */ 132 for (i=1; i<5; i++) { 133 if (base >= base_try[i]) { 134 PetscCall(PetscExp10((double)*power,&e10)); 135 base = base_try[i-1] * e10; 136 if (i == 1) *power = *power + 1; 137 break; 138 } 139 } 140 *Base = base; 141 PetscFunctionReturn(0); 142 } 143