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78 lines
2.0 KiB
78 lines
2.0 KiB
4 months ago
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21 Oct 2002
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bug fix in e_pow.c from "David G Hough at validlab.com" <validlab@validlab.com>.
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credit for bug report goes to andrew_johnson@uk.ibm.com
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test example:
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-----------------------------
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static int fail=0;
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trypow(x,y,z)
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double x,y,z;
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{
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extern double ieee_pow();
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double p ;
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p = ieee_pow(x,y);
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if (p != z) {
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printf(" pow failure x %e y %e computed %e correct %e \n",x,y,p,z);
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fail++;
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return;
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}
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if (1/p != 1/z) {
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printf(" pow failure x %e y %e computed %e correct %e \n",x,y,p,z);
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fail++;
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return;
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}
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}
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main()
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{
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trypow( 1.0000000001, 1.0000000001E10, 2.7182820535066154);
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trypow(-1.0000000001, 1.0000000001E10, -2.7182820535066154);
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trypow(-0.001, 1.0000000001E10, -0.0);
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trypow(-1000.0, 1.0000000001E10, -1.0/0.0);
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if (fail == 0) {
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printf(" fdlibm e_pow.c seems to be current \n");
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exit(0);
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}
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else {
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printf(" fdlibm e_pow.c seems to be out of date \n");
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exit(1);
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}
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}
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-----------------------------
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What's new in FDLIBM 5.3?
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CONFIGURE
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To build FDLIBM, edit the supplied Makefile or create
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a local Makefile by running "sh configure"
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using the supplied configure script contributed by Nelson Beebe
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BUGS FIXED
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1. e_pow.c incorrect results when
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x is very close to -1.0 and y is very large, e.g.
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ieee_pow(-1.0000000000000002e+00,4.5035996273704970e+15) = 0
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ieee_pow(-9.9999999999999978e-01,4.5035996273704970e+15) = 0
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Correct results are close to -e and -1/e.
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2. k_tan.c error was > 1 ulp target for FDLIBM
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5.2: Worst error at least 1.45 ulp at
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ieee_tan(1.7765241907548024E+269) = 1.7733884462610958E+16
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5.3: Worst error 0.96 ulp
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NOT FIXED YET
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3. Compiler failure on non-standard code
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Statements like
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*(1+(int*)&t1) = 0;
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are not standard C and cause some optimizing compilers (e.g. GCC)
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to generate bad code under optimization. These cases
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are to be addressed in the next release.
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