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