Implement scientific and engineering notations
These are only available when extra math is enabled because they are
implemented using shifting.
This bc/dc now accepts scientific/engineering notation for input, using
a lowercase 'e' as the exponent start. Either positive or negative
exponents are allowed, and the notation does not have to be correct
(i.e., both programs are liberal in what they accept, whether the
decimal point is in the correct position or not).
For outputting in scientific notation, set `obase` to `0`. This was used
because `0` is not a valid `obase` in other contexts, and doing it this
way instead of a function allows dc to have access to the same feature.
For outputting in engineering mode, set `obase` to `1` (which is also
not valid in other contexts).
For dc, negative exponents use underscore ('_').
diff --git a/src/num.c b/src/num.c
index 2f93f25..efce793 100644
--- a/src/num.c
+++ b/src/num.c
@@ -197,7 +197,7 @@
bc_num_clean(a);
}
-static void bc_num_shift(BcNum *restrict n, size_t places) {
+static void bc_num_shift_l(BcNum *restrict n, size_t places) {
if (!places || BC_NUM_ZERO(n)) return;
@@ -210,6 +210,27 @@
bc_num_clean(n);
}
+#if BC_ENABLE_EXTRA_MATH
+static void bc_num_shift_r(BcNum *restrict n, size_t places) {
+
+ size_t len;
+
+ len = n->rdx + places;
+
+ if (len > n->len) {
+
+ if (len > n->cap) bc_num_expand(n, len);
+
+ memset(n->num + n->len, 0, len - n->len);
+ n->len = len;
+ }
+
+ n->rdx += places;
+
+ assert(n->rdx <= n->len && n->len <= n->cap);
+}
+#endif // BC_ENABLE_EXTRA_MATH
+
static BcStatus bc_num_inv(BcNum *a, BcNum *b, size_t scale) {
BcNum one;
@@ -458,8 +479,8 @@
s = bc_num_sub(&temp, &z2, &z1, 0);
if (s) goto err;
- bc_num_shift(&z0, max2 * 2);
- bc_num_shift(&z1, max2);
+ bc_num_shift_l(&z0, max2 * 2);
+ bc_num_shift_l(&z1, max2);
s = bc_num_add(&z0, &z1, &temp, 0);
if (s) goto err;
s = bc_num_add(&temp, &z2, c, 0);
@@ -494,8 +515,8 @@
cpa.neg = cpb.neg = false;
- bc_num_shift(&cpa, maxrdx);
- bc_num_shift(&cpb, maxrdx);
+ bc_num_shift_l(&cpa, maxrdx);
+ bc_num_shift_l(&cpb, maxrdx);
s = bc_num_k(&cpa, &cpb, c);
if (s) goto err;
@@ -732,7 +753,7 @@
s = bc_num_intop(a, b, c, &val);
if (s) return s;
- bc_num_shift(c, val);
+ bc_num_shift_l(c, (size_t) val);
return s;
}
@@ -741,7 +762,6 @@
BcStatus s = BC_STATUS_SUCCESS;
unsigned long val = 0;
- size_t len;
BC_UNUSED(scale);
@@ -750,19 +770,7 @@
if (BC_NUM_ZERO(c)) return s;
- len = c->rdx + val;
-
- if (len > c->len) {
-
- if (len > c->cap) bc_num_expand(c, len);
-
- memset(c->num + c->len, 0, len - c->len);
- c->len = len;
- }
-
- c->rdx += val;
-
- assert(c->rdx <= c->len && c->len <= c->cap);
+ bc_num_shift_r(c, (size_t) val);
return s;
}
@@ -1006,6 +1014,54 @@
bc_num_printHex((size_t) n->num[i], 1, i == rdx);
}
+#if BC_ENABLE_EXTRA_MATH
+static void bc_num_printExponent(const BcNum *restrict n, bool eng) {
+
+ bool neg = (n->len <= n->rdx);
+ BcNum temp, exp;
+ size_t places, mod;
+ BcDig digs[BC_NUM_LONG_LOG10];
+
+ bc_num_createCopy(&temp, n);
+
+ if (neg) {
+ places = n->rdx - bc_num_len(n) + 1;
+ mod = places % 3;
+ if (eng && mod != 0) places += 3 - mod;
+ bc_num_shift_l(&temp, places);
+ }
+ else {
+ places = BC_NUM_INT(n) - 1;
+ mod = places % 3;
+ if (eng && mod != 0) places -= 3 - (3 - mod);
+ bc_num_shift_r(&temp, places);
+ }
+
+ bc_num_printDecimal(&temp);
+
+ bc_num_printNewline();
+ bc_vm_putchar('e');
+
+ if (!places) {
+ bc_num_printHex(0, 1, false);
+ goto exit;
+ }
+
+ if (neg) {
+ bc_num_printNewline();
+ bc_vm_putchar('-');
+ }
+
+ bc_num_setup(&exp, digs, BC_NUM_LONG_LOG10);
+ bc_num_ulong2num(&exp, (unsigned long) places);
+
+ bc_num_printDecimal(&exp);
+
+exit:
+ bc_num_free(&temp);
+}
+#endif // BC_ENABLE_EXTRA_MATH
+
static BcStatus bc_num_printNum(BcNum *restrict n, BcNum *restrict base,
size_t len, BcNumDigitOp print)
{
@@ -1162,6 +1218,20 @@
bc_num_ulong2num(n, val);
}
+size_t bc_num_scale(const BcNum *restrict n) {
+ return n->rdx;
+}
+
+size_t bc_num_len(const BcNum *restrict n) {
+
+ size_t i, len = n->len;
+
+ if (n->rdx != n->len) return len;
+ for (i = n->len - 1; i < n->len && !n->num[i]; --len, --i);
+
+ return len;
+}
+
BcStatus bc_num_parse(BcNum *restrict n, const char *restrict val,
BcNum *restrict base, size_t base_t, bool letter)
{
@@ -1184,12 +1254,15 @@
BcStatus s = BC_STATUS_SUCCESS;
assert(n && base);
- assert(base_t >= BC_NUM_MIN_BASE);
+ assert(BC_ENABLE_EXTRA_MATH || base_t >= BC_NUM_MIN_BASE);
bc_num_printNewline();
if (BC_NUM_ZERO(n)) bc_num_printHex(0, 1, false);
else if (base_t == 10) bc_num_printDecimal(n);
+#if BC_ENABLE_EXTRA_MATH
+ else if (base_t == 0 || base_t == 1) bc_num_printExponent(n, base_t != 0);
+#endif // BC_ENABLE_EXTRA_MATH
else s = bc_num_printBase(n, base, base_t);
if (!s && newline) {