1 #include <petsc/private/drawimpl.h> /*I "petscdraw.h" I*/ 2 3 /* 4 val is the label value. sep is the separation to the next (or previous) 5 label; this is useful in determining how many significant figures to 6 keep. 7 */ 8 PetscErrorCode PetscADefLabel(PetscReal val, PetscReal sep, char **p) 9 { 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 PetscCall(PetscSNPrintf(buf, PETSC_STATIC_ARRAY_LENGTH(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(PETSC_SUCCESS); 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; 44 eps = base / 10; 45 while (i < maxtick && x <= high + eps) { 46 tickloc[i++] = x; 47 x += base; 48 } 49 *ntick = i; 50 tickloc[i - 1] = PetscMin(tickloc[i - 1], high); 51 52 if (i < 2 && num < 10) PetscCall(PetscADefTicks(low, high, num + 1, ntick, tickloc, maxtick)); 53 PetscFunctionReturn(PETSC_SUCCESS); 54 } 55 56 #define EPS 1.e-6 57 58 static PetscErrorCode PetscExp10(PetscReal d, PetscReal *result) 59 { 60 PetscFunctionBegin; 61 *result = PetscPowReal((PetscReal)10.0, d); 62 PetscFunctionReturn(PETSC_SUCCESS); 63 } 64 65 static 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(PETSC_SUCCESS); 73 } 74 i = ((int)x) / ((int)y); 75 x = x - ((PetscReal)i) * y; 76 while (x > y) x -= y; 77 *result = x; 78 PetscFunctionReturn(PETSC_SUCCESS); 79 } 80 81 static PetscErrorCode PetscCopysign(PetscReal a, PetscReal b, PetscReal *result) 82 { 83 PetscFunctionBegin; 84 if (b >= 0) *result = a; 85 else *result = -a; 86 PetscFunctionReturn(PETSC_SUCCESS); 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(PETSC_SUCCESS); 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(PETSC_SUCCESS); 142 } 143