Opened 12 years ago

Closed 8 years ago

# special values of lesser hyperbolic functions

Reported by: Owned by: kcrisman burcin minor sage-6.4 symbolics sech, coth, csch Ralf Stephan Frédéric Chapoton N/A e064ff3 e064ff3a8cc50f28ccdac848c4eab688875d26e8

### Description

Even though Maxima can evaluate `sech(0)`, Sage does this:

```sage: cosh(0)
1
sage: sech(0)
sech(0)
```

It seems reasonable to fix this. Part of this is probably that `sech` is not a !GiNaC function.

### comment:1 Changed 11 years ago by benjaminfjones

Is there a way of initializing a Ginac / Pynac function using a symbolic expression? It would be nice to be able to initialize `sech` by calling simply:

```GinacExpression.__init__(self, '1/cosh', ...
```

And the result would behave just like defining `sech(z) = 1/cosh(z)` in Sage. Then we'd get (as in sage-5.0.beta9):

```sage: sech(z) = 1/cosh(z)
sage: sech(0)
1
```

Maybe this is naive...

### comment:2 Changed 9 years ago by jdemeyer

Milestone: sage-5.11 → sage-5.12

### comment:3 Changed 9 years ago by vbraun_spam

Milestone: sage-6.1 → sage-6.2

### comment:4 Changed 9 years ago by vbraun_spam

Milestone: sage-6.2 → sage-6.3

### comment:5 Changed 8 years ago by vbraun_spam

Milestone: sage-6.3 → sage-6.4

### comment:6 Changed 8 years ago by rws

Summary: Improve less-used hyperbolic functions → special values of lesser hyperbolic functions

### comment:7 Changed 8 years ago by rws

Branch: → u/rws/improve_less_used_hyperbolic_functions

### comment:8 Changed 8 years ago by rws

Authors: → Ralf Stephan → b1833cb5e3f2e204e4ec966e404a42835a82f418 new → needs_review

New commits:

 ​b1833cb `10074: special values of coth, sech, csch`

### comment:9 Changed 8 years ago by chapoton

Status: needs_review → needs_work

### comment:10 Changed 8 years ago by git

Branch pushed to git repo; I updated commit sha1. New commits:

 ​507dc57 `10074: cosmetics`

### comment:11 Changed 8 years ago by rws

Status: needs_work → needs_review

### comment:12 Changed 8 years ago by chapoton

Branch: u/rws/improve_less_used_hyperbolic_functions → public/ticket/10074 507dc57324d5cdada41940aa9d61120c0846f95a → e064ff3a8cc50f28ccdac848c4eab688875d26e8 → Frédéric Chapoton

Looks good to me, if you agree with my small changes, you can set that to pos.rev.

New commits:

 ​16323a3 `Merge branch 'u/rws/improve_less_used_hyperbolic_functions' into 6.5.b6` ​e064ff3 `trac #10074 review commit`

### comment:13 Changed 8 years ago by rws

Status: needs_review → positive_review

OK. Thanks.

### comment:14 Changed 8 years ago by vbraun

Branch: public/ticket/10074 → e064ff3a8cc50f28ccdac848c4eab688875d26e8 → fixed positive_review → closed
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