projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 7049871b TL |
1 | # double tanh(arg) |
| 2 | # double arg | |
| 3 | # method: tanh(arg)=sinh(arg)/cosh(arg); if |arg|<0.5 sinh(9 is computed from | |
| 4 | # a polynomial approx otherwise from exp(). | |
| 5 | # Only 1 call to exp(9 is made. | |
| 6 | # J F Jarvis, August 17, 1978 | |
| 7 | .globl _tanh | |
| 8 | .globl _exp | |
| 9 | .text | |
| 10 | .align 1 | |
| 11 | _tanh: | |
| 12 | .word 0x7c0 | |
| 13 | clrl r10 # sign bit | |
| 14 | movd 4(ap),r6 | |
| 15 | jgeq t1 | |
| 16 | movw $0x8000,r10 | |
| 17 | xorw2 r10,r6 # co|arg| | |
| 18 | t1: cmpd r6,$0d2.0e+1 | |
| 19 | jleq t2 | |
| 20 | movd $0d1.0e+0,r0 | |
| 21 | xorw2 r10,r0 | |
| 22 | ret | |
| 23 | t2: movd r6,-(sp) | |
| 24 | calls $2,_exp | |
| 25 | movd r0,r8 | |
| 26 | divd3 r8,$0d1.0e+0,-(sp) # exp(-|arg|) | |
| 27 | cmpd r6,$0d0.5e+0 | |
| 28 | jgeq t3 | |
| 29 | muld3 r6,r6,r0 # |arg|<0.5, sinh() from poly approx | |
| 30 | polyd r0,$5,pcoef | |
| 31 | muld2 r6,r0 | |
| 32 | muld2 $0d2.0e+0,r0 | |
| 33 | jbr t4 | |
| 34 | t3: subd3 (sp),r8,r0 | |
| 35 | t4: # r0,1 = 2*sinh(|arg|) | |
| 36 | addd3 (sp),r8,r2 # r2,3 = cosh(|arg|); | |
| 37 | divd2 r2,r0 # r0,1 = tanh(|arg|) | |
| 38 | xorw2 r10,r0 # r0,1 = tanh(arg) | |
| 39 | ret | |
| 40 | .data | |
| 41 | .align 3 | |
| 42 | pcoef: | |
| 43 | .double 0d0.251726188251e-7 | |
| 44 | .double 0d0.275569807356154e-5 | |
| 45 | .double 0d0.1984127027907999e-3 | |
| 46 | .double 0d0.833333333307759961e-2 | |
| 47 | .double 0d0.16666666666667212324e+0 | |
| 48 | .double 0d0.99999999999999998116e+0 |