X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Fmath%2Fchart-geometry.c;h=7029ddd73714a1f453c85943d4048a7387fce438;hb=261e25786073840d341ffdd5c36a08b0b9e46504;hp=35380a6929b6c4529e0fe2d5579e03cad9b25f23;hpb=0df9cdd3df66caf4353128feff3008289cda8115;p=pspp diff --git a/src/math/chart-geometry.c b/src/math/chart-geometry.c index 35380a6929..7029ddd737 100644 --- a/src/math/chart-geometry.c +++ b/src/math/chart-geometry.c @@ -20,63 +20,28 @@ #include #include "chart-geometry.h" -#include "decimal.h" #include -static const double standard_tick[] = {1, 2, 5, 10}; - -/* Adjust tick to be a sensible value - ie: ... 0.1,0.2,0.5, 1,2,5, 10,20,50 ... */ -void -chart_rounded_tick (double tick, struct decimal *result) -{ - int i; - - struct decimal ddif = {1, 1000}; - - /* Avoid arithmetic problems with very small values */ - if (fabs (tick) < DBL_EPSILON) - { - result->ordinate = 0; - result->mantissa = 0; - return; - } +#include "gl/xalloc.h" +#include "gl/minmax.h" +#include "gl/xvasprintf.h" - struct decimal dt; - decimal_from_double (&dt, tick); - - double expd = dec_log10 (&dt) - 1; +#include "gettext.h" +#define _(msgid) gettext (msgid) - for (i = 0 ; i < 4 ; ++i) - { - struct decimal candidate; - struct decimal delta; - - decimal_init (&candidate, standard_tick[i], expd); - - delta = dt; - decimal_subtract (&delta, &candidate); - delta.ordinate = llabs (delta.ordinate); - - if (decimal_cmp (&delta, &ddif) < 0) - { - ddif = delta; - *result = candidate; - } - } -} +static const double standard_tick[] = {1, 2, 5, 10}; -/* +/* Find a set {LOWER, INTERVAL, N_TICKS} such that: LOWER <= LOWDBL, LOWER + INTERVAL > LOWDBL, - + LOWER + N_TICKS * INTERVAL < HIGHDBL LOWER + (N_TICKS + 1) * INTERVAL >= HIGHDBL INTERVAL = X * 10^N - where: N is integer + where: N is integer and X is an element of {1, 2, 5} In other words: @@ -88,64 +53,145 @@ chart_rounded_tick (double tick, struct decimal *result) ^LOWDBL ^HIGHDBL */ void -chart_get_scale (double highdbl, double lowdbl, - struct decimal *lower, - struct decimal *interval, +chart_get_scale (double high, double low, + double *lower, double *interval, int *n_ticks) { int i; double fitness = DBL_MAX; + double logrange; *n_ticks = 0; - struct decimal high; - struct decimal low; - assert (highdbl >= lowdbl); + assert (high >= low); - decimal_from_double (&high, highdbl); - decimal_from_double (&low, lowdbl); - - struct decimal diff = high; - decimal_subtract (&diff, &low); + if ((high - low) < 10 * DBL_MIN) { + *n_ticks = 0; + *lower = low; + *interval = 0.0; + return; + } - double expd = dec_log10 (&diff) - 2; + logrange = floor(log10(high-low)); /* Find the most pleasing interval */ for (i = 1; i < 4; ++i) { - struct decimal clbound = low; - struct decimal cubound = high; - struct decimal candidate; - decimal_init (&candidate, standard_tick[i], expd); - - decimal_divide (&clbound, &candidate); - int fl = decimal_floor (&clbound); - decimal_int_multiply (&candidate, fl); - clbound = candidate; + double cinterval = standard_tick[i] * pow(10.0,logrange-1); + double clower = floor(low/cinterval) * cinterval; + int cnticks = ceil((high - clower) / cinterval)-1; + double cfitness = fabs(7.5 - cnticks); + + if (cfitness < fitness) { + fitness = cfitness; + *lower = clower; + *interval = cinterval; + *n_ticks = cnticks; + } + } +} +/* + Generate a format string which can be passed to printf like functions, + which will produce a string in scientific notation representing a real + number. N_DECIMALS is the number of decimal places EXPONENT is the + value of the exponent. +*/ +static inline char * +gen_pango_markup_scientific_format_string (int n_decimals, int exponent) +{ + /* TRANSLATORS: This is a format string which, when presented to + printf like functions, will create a pango markup string to + display real number in scientific notation. - decimal_init (&candidate, standard_tick[i], expd); - decimal_divide (&cubound, &candidate); - int fu = decimal_ceil (&cubound); - decimal_int_multiply (&candidate, fu); + In its untranslated form, it will display similar to "1.23 x 10^4". You + can leave it untranslated if this is how scientific notation is usually + presented in your language. - cubound = candidate; + Some locales (such as German) prefer the centered dot rather than the + multiplication sign between the mantissa an exponent. In which + case, you can change "#215;" to "#8901;" or other unicode code + point as appropriate. - decimal_init (&candidate, standard_tick[i], expd); - decimal_subtract (&cubound, &clbound); - decimal_divide (&cubound, &candidate); + The . in this string does not and should not be changed, since + that is taken care of by the stdc library. + For information on Pango markup, see + http://developer.gnome.org/pango/stable/PangoMarkupFormat.html - ord_t n_int = decimal_floor (&cubound); + For tables of unicode code points, see http://unicode.org/charts + */ + return xasprintf(_("%%.%dlf×10%d"), n_decimals, exponent); +} - /* We prefer to have between 5 and 10 tick marks on a scale */ - double f = 1 - exp (-0.2 * fabs (n_int - 7.5) / 7.5); +/* + * Compute the optimum format string and the scaling + * for the tick drawing on a chart axis + * Input: lower: the lowest tick + * interval:the interval between the ticks + * nticks: the number of tick intervals (bins) on the axis + * Return: fs: format string for printf to print the tick value + * scale: scaling factor for the tick value + * The format string has to be freed after usage. + * An example format string and scalefactor: + * Non Scientific: "%.3lf", scale=1.00 + * Scientific: "%.2lfe3", scale = 0.001 + * Usage example: + * fs = chart_get_ticks_format(-0.7,0.1,8,&scale); + * printf(fs,value*scale); + * free(fs); + */ +char * +chart_get_ticks_format (const double lower, const double interval, + const unsigned int nticks, double *scale) +{ + double logmax = log10(fmax(fabs(lower + (nticks+1)*interval),fabs(lower))); + double logintv = log10(interval); + int logshift = 0; + char *format_string = NULL; + int nrdecs = 0; - if (f < fitness) + if (logmax > 0.0 && logintv < 0.0) + { + nrdecs = MIN(6,(int)(ceil(fabs(logintv)))); + logshift = 0; + if (logmax < 12.0) + format_string = xasprintf("%%.%dlf",nrdecs); + else + format_string = xasprintf("%%lg"); + } + else if (logmax > 0.0) /*logintv is > 0*/ + { + if (logintv < 5.0 && logmax < 10.0) + { + logshift = 0; /* No scientific format */ + nrdecs = 0; + format_string = xstrdup("%.0lf"); + } + else { - fitness = f; - *lower = clbound; - *interval = candidate; - *n_ticks = n_int; + logshift = (int)logmax; + /* Possible intervals are 0.2Ex, 0.5Ex, 1.0Ex */ + /* log10(0.2E9) = 8.30, log10(0.5E9) = 8.69, log10(1.0E9) = 9 */ + /* 0.2 and 0.5 need one decimal more. For stability subtract 0.1 */ + nrdecs = MIN(8,(int)(ceil(logshift-logintv-0.1))); + format_string = gen_pango_markup_scientific_format_string (nrdecs, logshift); } } + else /* logmax and logintv are < 0 */ + { + if (logmax > -3.0) + { + logshift = 0; /* No scientific format */ + nrdecs = MIN(8,(int)(ceil(-logintv))); + format_string = xasprintf("%%.%dlf",nrdecs); + } + else + { + logshift = (int)logmax-1; + nrdecs = MIN(8,(int)(ceil(logshift-logintv-0.1))); + format_string = gen_pango_markup_scientific_format_string (nrdecs, logshift); + } + } + *scale = pow(10.0,-(double)logshift); + return format_string; }