## 28 Reputation

18 years, 196 days

## Old bug in 10.03?...

I remember, that similar bug was in the 10.0. Now I found it in 10.03. How to reproduce it: 1) Create new worksheet 2) Enter and execute next statements (using ctrl-L to enter referencies to formulas): ``` >exp(-y^3/x)*y/x^(4/3); ... (1) >1-a*x; ... (2) >assume(y,positive); >inttrans[laplace]((1),x,s); ... (3) >inttrans[laplace]((2),x,s); ... (4) >inttrans[invlaplace]((3)*(4),s,x) ... (5) >plot(subs(x=1,a=1,inttrans[invlaplace]((3)*(4),s,x)),y=0..3) ```

## Invalid evaluation of derivative (more e...

Additionally to my previous post: First example returns (mathematically) wrong result,
```eval(diff(v(z), z), [v = (x->x*H), z = H])
2H
```
Equivalent works fine (just because multiplier "a" leads to implicit conversion of diff to D).
```eval(diff(v(a*z), z), [v = (x->x*H), z = H, a = 1])
H
```
And the most exiting example (I think, that result can't be predicted by Maple developers also ):)))
```eval(diff(v(x, y), x, y), {x = H, y = H})
(D[1,1](v))(H,H)+2 (D[1,2](v))(H,H)+(D[2,2](v))(H,H)
```
Functional analog works, of course, without any errors.

## Invalid evaluation of derivative (Maple ...

Maple 10

Create new document (or worksheet) with content below and execute it step by step: > restart; > Eval(diff(v(z),z),z=H)==eval(diff(v(z),z),z=H); Eval(diff(v(z),z),z=H)=diff(v(H),H) > v:=z->z*H; v:=z->z*H > value((1)); H=2H As you can see, result of eval, which in this case is equivalent to subs(z=H,diff(v(z),z)), at the right side of first equation leads to wrong final result :( This...

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