How to make calc-symbolic-mode apply to sin
reddit / emacs

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Isaac22877822 · 2022-06-11 09:56

So I've just started playing with calc mode and it's amazing. However
I found one problem: symbolic-mode doesn't seem to affect sin. When I
push 2 onto the stack and type S it evaluates to a float even with
symbolic mode enabled. The same does not happen with square roots.

​

Here's my calc.el

    (setq calc-display-trail nil)
    (setq calc-symbolic-mode t)
    (setq calc-angle-mode 'rad)
    (setq calc-simplify-mode 'none)
    (setq calc-complex-format 'i)
    (setq calc-prefer-frac t)


If anyone knows anything I'd appreciate some help, if not checkout
calc mode, it's really cool.

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simbledress · 2022-06-18 06:49

IIUC `symbolic-mode` is only for *inexact* computations. `sin(2)` is
not irrational.

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Isaac22877822 · 2022-06-20 22:45

Thanks for looking into this. I'm not sure that sin 2 is rational. I
couldn't prove it either way. Regardless I have the same behavior for
sin 1 which is
[definitely](https://math.stackexchange.com/questions/1124435/proving-
that-sin1-radian-is-irrational-without-using-taylor-series-expansio)
irrational. So I think it might be a bug.