Dsolve : Unable to solve diff(y) = -y

Qalculate / libqalculate

Qalculate! library and CLI

https://qalculate.github.io/

GNU General Public License v2.0

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Dsolve : Unable to solve diff(y) = -y #623

Closed kernelb00t closed 4 months ago

kernelb00t commented 9 months ago

> dsolve(diff(y) = -y)

  error: No differential equation found.
  dsolve(diff(y) = (−y)) = dsolve(y + diff(y) = 0)

But :

Is it me not kowing how dsolve is working? Or is it Dsolve just behaving weirdly?

Computer :

Arch Linux latest

3 extra/libqalculate 4.9.0-2 (2.7 MiB 14.9 MiB) (Installed)
Multi-purpose desktop calculator
2 extra/qalculate-gtk 4.9.0-1 (2.4 MiB 6.0 MiB) (Installed)
GTK frontend for libqalculate

Intel CPU

hanna-kn commented 9 months ago

> dsolve(diff(y, x) = −y)

  dsolve(diff(y, x) = (−y)) = C / e^x ≈ 0.3678794412^x × C

Note however that version 4.9.0 is unable to isolate x because C is not assumed real (see https://github.com/Qalculate/libqalculate/issues/617).