CODEWITHSUNDEEP
pythonwolfram-mathematica
Uwe.Schneider
Uwe.Schneider

Reputation: 1415

Error for DSolve (Wolfram Mathematica in Python)

usually, I can call Mathematica functions in Python by constructing the string that I would give in a Mathematica notebook. This works for the first example, but not for the second one.

  1. Example
from wolframclient.evaluation import WolframLanguageSession
from wolframclient.language import wl, wlexpr
session = WolframLanguageSession()

alpha = wlexpr("Integrate[1/(x^3 + 1), {x, 0, 1}]")
result = session.evaluate(alpha)
print(result,"   ",type(result))
  1. Example
from wolframclient.evaluation import WolframLanguageSession
from wolframclient.language import wl, wlexpr
session = WolframLanguageSession()

diff_0 = "DSolve[y'[x] + y[x] == a Sin[x], y[x], x]"
diff_1 = "DSolve[{y'[x] + y[x] == a Sin[x], y[0] == 0}, y, x]"
diff_2 = "DSolve[y'[x] + y[x] == a Sin[x], y[x], x]"

alpha = wlexpr(diff_0)
result = session.evaluate(alpha)
print(result,"   ",result)

The second example gives me errors. Is this a problem of "DSolve" being called in Python?

The error reads

String expected at position 1 in StringForm[MessageName[General, pkspec1], Slot[1]].
The expression Slot[1] cannot be used as a part specification.
String expected at position 1 in StringForm[MessageName[General, pkspec1], i].
The expression i cannot be used as a part specification.
String expected at position 1 in StringForm[MessageName[General, pkspec1], Slot[1]].
The expression Slot[1] cannot be used as a part specification.
String expected at position 1 in StringForm[MessageName[General, pkspec1], i].
The expression i cannot be used as a part specification.

Upvotes: 0

Views: 251

Answers (1)

Bill
Bill

Reputation: 3977

Just as a quick check for you to be able to verify that Mathematica can do your second examples, if I open my web browser and I go to Wolfram Link

and I patiently wait for it to finish displaying "Type your Wolfram Language Input..."

and I give one left mouse click in the large empty white box below that

and I tap the "x" key and patiently wait for it to appear

and I tap the backspace key and patiently wait for it to disappear

and I paste the following from my clipboard and patiently wait for it to appear

DSolve[y'[x] + y[x] == a Sin[x], y[x], x]
DSolve[{y'[x] + y[x] == a Sin[x], y[0] == 0}, y, x]
DSolve[y'[x] + y[x] == a Sin[x], y[x], x]

and I press and hold Shift while I tap Enter

and I patiently wait until this appears

{{y[x] -> C[1]/E^x + (a*(-Cos[x] + Sin[x]))/2}}
{{y -> Function[{x}, -(a*(-1 + E^x*Cos[x] - E^x*Sin[x]))/(2*E^x)]}}
{{y[x] -> C[1]/E^x + (a*(-Cos[x] + Sin[x]))/2}}

which seems to indicate that Mathematica is able to correctly understand and evaluate that.

See if you are able to carefully reproduce these steps.

This does nothing to look at your communication between Python and Mathematica. All this does is try to verify that Mathematica is able to understand those differential equations and find solutions.

That is a very nice free service with fairly tight limitations on the size of problems and time it can take to check calculations. Please do not abuse that. Thank you.

Upvotes: 1

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