|
5 | 5 | * |
6 | 6 | *1998 Jan Wieck |
7 | 7 | * |
8 | | - * $Header: /cvsroot/pgsql/src/backend/utils/adt/numeric.c,v 1.36 2000/12/07 02:47:35 tgl Exp $ |
| 8 | + * $Header: /cvsroot/pgsql/src/backend/utils/adt/numeric.c,v 1.37 2001/03/14 16:50:37 tgl Exp $ |
9 | 9 | * |
10 | 10 | * ---------- |
11 | 11 | */ |
@@ -3355,16 +3355,19 @@ mod_var(NumericVar *var1, NumericVar *var2, NumericVar *result) |
3355 | 3355 | init_var(&tmp); |
3356 | 3356 |
|
3357 | 3357 | /* ---------- |
3358 | | - * We do it by fiddling around with global_rscale and truncating |
3359 | | - * the result of the division. |
| 3358 | + * We do this using the equation |
| 3359 | + *mod(x,y) = x - trunc(x/y)*y |
| 3360 | + * We fiddle a bit with global_rscale to control result precision. |
3360 | 3361 | * ---------- |
3361 | 3362 | */ |
3362 | 3363 | save_global_rscale=global_rscale; |
3363 | 3364 | global_rscale=var2->rscale+2; |
3364 | 3365 |
|
3365 | 3366 | div_var(var1,var2,&tmp); |
| 3367 | + |
| 3368 | +/* do trunc() by forgetting digits to the right of the decimal point */ |
| 3369 | +tmp.ndigits=MAX(0,MIN(tmp.ndigits,tmp.weight+1)); |
3366 | 3370 | tmp.rscale=var2->rscale; |
3367 | | -tmp.ndigits=MAX(0,MIN(tmp.ndigits,tmp.weight+tmp.rscale+1)); |
3368 | 3371 |
|
3369 | 3372 | global_rscale=var2->rscale; |
3370 | 3373 | mul_var(var2,&tmp,&tmp); |
|