diff options
| author | Eric Andersen <andersen@codepoet.org> | 2001-10-02 10:45:16 +0000 |
|---|---|---|
| committer | Eric Andersen <andersen@codepoet.org> | 2001-10-02 10:45:16 +0000 |
| commit | f108799afa9b1d207e7139608c261f5546eb56bf (patch) | |
| tree | b84ad7a12eb961ca185c83b45098d5fc23ecd1ae /test/math/eexp.c | |
| parent | 04dafe547980c50bef57b3ea7a4f9e3d81400a87 (diff) | |
Add in some math lib tests
Diffstat (limited to 'test/math/eexp.c')
| -rw-r--r-- | test/math/eexp.c | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/test/math/eexp.c b/test/math/eexp.c new file mode 100644 index 000000000..dd2a64e1c --- /dev/null +++ b/test/math/eexp.c @@ -0,0 +1,77 @@ +/* xexp.c */
+/* exponential function check routine */
+/* by Stephen L. Moshier. */
+
+
+#include "ehead.h"
+
+/*
+extern int powinited;
+extern short maxposint[], maxnegint[];
+*/
+
+void eexp( x, y )
+unsigned short *x, *y;
+{
+unsigned short num[NE], den[NE], x2[NE];
+long i;
+unsigned short sign, expchk;
+
+/* range reduction theory: x = i + f, 0<=f<1;
+ * e**x = e**i * e**f
+ * e**i = 2**(i/log 2).
+ * Let i/log2 = i1 + f1, 0<=f1<1.
+ * Then e**i = 2**i1 * 2**f1, so
+ * e**x = 2**i1 * e**(log 2 * f1) * e**f.
+ */
+/*
+if( powinited == 0 )
+ initpow();
+*/
+if( ecmp(x, ezero) == 0 )
+ {
+ emov( eone, y );
+ return;
+ }
+emov(x, x2);
+expchk = x2[NE-1];
+sign = expchk & 0x8000;
+x2[NE-1] &= 0x7fff;
+
+/* Test for excessively large argument */
+expchk &= 0x7fff;
+if( expchk > (EXONE + 15) )
+ {
+ eclear( y );
+ if( sign == 0 )
+ einfin( y );
+ return;
+ }
+
+eifrac( x2, &i, num ); /* x = i + f */
+
+if( i != 0 )
+ {
+ ltoe( &i, den ); /* floating point i */
+ ediv( elog2, den, den ); /* i/log 2 */
+ eifrac( den, &i, den ); /* i/log 2 = i1 + f1 */
+ emul( elog2, den, den ); /* log 2 * f1 */
+ eadd( den, num, x2 ); /* log 2 * f1 + f */
+ }
+
+/*x2[NE-1] -= 1;*/
+eldexp( x2, -1L, x2 ); /* divide by 2 */
+etanh( x2, x2 ); /* tanh( x/2 ) */
+eadd( x2, eone, num ); /* 1 + tanh */
+eneg( x2 );
+eadd( x2, eone, den ); /* 1 - tanh */
+ediv( den, num, y ); /* (1 + tanh)/(1 - tanh) */
+
+/*y[NE-1] += i;*/
+if( sign )
+ {
+ ediv( y, eone, y );
+ i = -i;
+ }
+eldexp( y, i, y ); /* multiply by 2**i */
+}
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