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'; 17 buf[1] = 0; 18 } else { 19 PetscCall(PetscSNPrintf(buf, PETSC_STATIC_ARRAY_LENGTH(buf), "%0.1e", (double)val)); 20 PetscCall(PetscStripZerosPlus(buf)); 21 PetscCall(PetscStripe0(buf)); 22 PetscCall(PetscStripInitialZero(buf)); 23 PetscCall(PetscStripAllZeros(buf)); 24 PetscCall(PetscStripTrailingZeros(buf)); 25 } 26 *p = buf; 27 PetscFunctionReturn(PETSC_SUCCESS); 28 } 29 30 /* Finds "nice" locations for the ticks */ 31 PetscErrorCode PetscADefTicks(PetscReal low, PetscReal high, int num, int *ntick, PetscReal *tickloc, int maxtick) 32 { 33 int i, power; 34 PetscReal x = 0.0, base = 0.0, eps; 35 36 PetscFunctionBegin; 37 PetscCall(PetscAGetBase(low, high, num, &base, &power)); 38 PetscCall(PetscAGetNice(low, base, -1, &x)); 39 40 /* Values are of the form j * base */ 41 /* Find the starting value */ 42 if (x < low) x += base; 43 44 i = 0; 45 eps = base / 10; 46 while (i < maxtick && x <= high + eps) { 47 tickloc[i++] = x; 48 x += base; 49 } 50 *ntick = i; 51 tickloc[i - 1] = PetscMin(tickloc[i - 1], high); 52 53 if (i < 2 && num < 10) PetscCall(PetscADefTicks(low, high, num + 1, ntick, tickloc, maxtick)); 54 PetscFunctionReturn(PETSC_SUCCESS); 55 } 56 57 #define EPS 1.e-6 58 59 PetscErrorCode PetscExp10(PetscReal d, PetscReal *result) 60 { 61 PetscFunctionBegin; 62 *result = PetscPowReal((PetscReal)10.0, d); 63 PetscFunctionReturn(PETSC_SUCCESS); 64 } 65 66 PetscErrorCode PetscMod(PetscReal x, PetscReal y, PetscReal *result) 67 { 68 int i; 69 70 PetscFunctionBegin; 71 if (y == 1) { 72 *result = 0.0; 73 PetscFunctionReturn(PETSC_SUCCESS); 74 } 75 i = ((int)x) / ((int)y); 76 x = x - i * y; 77 while (x > y) x -= y; 78 *result = x; 79 PetscFunctionReturn(PETSC_SUCCESS); 80 } 81 82 PetscErrorCode PetscCopysign(PetscReal a, PetscReal b, PetscReal *result) 83 { 84 PetscFunctionBegin; 85 if (b >= 0) *result = a; 86 else *result = -a; 87 PetscFunctionReturn(PETSC_SUCCESS); 88 } 89 90 /* 91 Given a value "in" and a "base", return a nice value. 92 based on "sign", extend up (+1) or down (-1) 93 */ 94 PetscErrorCode PetscAGetNice(PetscReal in, PetscReal base, int sign, PetscReal *result) 95 { 96 PetscReal etmp, s, s2, m; 97 98 PetscFunctionBegin; 99 PetscCall(PetscCopysign(0.5, (double)sign, &s)); 100 etmp = in / base + 0.5 + s; 101 PetscCall(PetscCopysign(0.5, etmp, &s)); 102 PetscCall(PetscCopysign(EPS * etmp, (double)sign, &s2)); 103 etmp = etmp - 0.5 + s - s2; 104 PetscCall(PetscMod(etmp, 1.0, &m)); 105 etmp = base * (etmp - m); 106 *result = etmp; 107 PetscFunctionReturn(PETSC_SUCCESS); 108 } 109 110 PetscErrorCode PetscAGetBase(PetscReal vmin, PetscReal vmax, int num, PetscReal *Base, int *power) 111 { 112 PetscReal base, ftemp, e10; 113 static PetscReal base_try[5] = {10.0, 5.0, 2.0, 1.0, 0.5}; 114 int i; 115 116 PetscFunctionBegin; 117 /* labels of the form n * BASE */ 118 /* get an approximate value for BASE */ 119 base = (vmax - vmin) / (double)(num + 1); 120 121 /* make it of form m x 10^power, m in [1.0, 10) */ 122 if (base <= 0.0) { 123 base = PetscAbsReal(vmin); 124 if (base < 1.0) base = 1.0; 125 } 126 ftemp = PetscLog10Real((1.0 + EPS) * base); 127 if (ftemp < 0.0) ftemp -= 1.0; 128 *power = (int)ftemp; 129 PetscCall(PetscExp10((double)-*power, &e10)); 130 base = base * e10; 131 if (base < 1.0) base = 1.0; 132 /* now reduce it to one of 1, 2, or 5 */ 133 for (i = 1; i < 5; i++) { 134 if (base >= base_try[i]) { 135 PetscCall(PetscExp10((double)*power, &e10)); 136 base = base_try[i - 1] * e10; 137 if (i == 1) *power = *power + 1; 138 break; 139 } 140 } 141 *Base = base; 142 PetscFunctionReturn(PETSC_SUCCESS); 143 } 144