CAS diff() giving incorrect results
09-24-2021, 10:48 AM
Post: #5
 Albert Chan Senior Member Posts: 2,708 Joined: Jul 2018
RE: CAS diff() giving incorrect results
(09-23-2021 06:20 PM)Wes Loewer Wrote:  When I try (x^3)''(x = 4) it gives a warning and returns (6*x) = 24,

When I try same expression in the emulator, above return only 24, without warning.
I beiieve (x^3)''(x = 4) equivalent to subst((x^3)'', x = 4), only less typing.

Quote:That's an interesting notation. It appears to work for other functions as well.

If the expression is not a function, the notation may get confused with implied multiply.

XCAS> (1+x+x^2) (x=0.1)

Warning : using implicit multiplication for (1+x+x^2)(x=0.1)
x*(x^2+x+1)=(0.1*(x^2+x+1))

CAS> (1+x+x^2) (x=0.1) ﻿ ﻿ ﻿ ﻿ ﻿ ﻿ ﻿ ﻿ → "Syntax Error"

We can get around the problem (both CAS and XCAS) with identity function.

CAS> id(1+x+x^2) (x=0.1) ﻿ ﻿ ﻿ ﻿ ﻿ ﻿ → 1.11
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 Messages In This Thread CAS diff() giving incorrect results - Wes Loewer - 09-22-2021, 07:10 PM RE: CAS diff() giving incorrect results - parisse - 09-22-2021, 07:26 PM RE: CAS diff() giving incorrect results - Wes Loewer - 09-23-2021, 06:20 PM RE: CAS diff() giving incorrect results - toml_12953 - 09-23-2021, 07:26 PM RE: CAS diff() giving incorrect results - Albert Chan - 09-24-2021 10:48 AM RE: CAS diff() giving incorrect results - Wes Loewer - 09-24-2021, 04:28 PM RE: CAS diff() giving incorrect results - Albert Chan - 09-24-2021, 05:23 PM RE: CAS diff() giving incorrect results - Wes Loewer - 09-24-2021, 07:59 PM RE: CAS diff() giving incorrect results - parisse - 09-25-2021, 04:04 PM RE: CAS diff() giving incorrect results - Albert Chan - 09-25-2021, 05:03 PM RE: CAS diff() giving incorrect results - Albert Chan - 09-26-2021, 12:04 PM

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