29.5.8 problem 123

Internal problem ID [4725]
Book : Ordinary differential equations and their solutions. By George Moseley Murphy. 1960
Section : Various 5
Problem number : 123
Date solved : Sunday, March 30, 2025 at 03:49:39 AM
CAS classification : [_quadrature]

\begin{align*} y^{\prime }&=a +b \sin \left (y\right ) \end{align*}

✓ Maple. Time used: 0.007 (sec). Leaf size: 44

ode:=diff(y(x),x) = a+b*sin(y(x)); 
dsolve(ode,y(x), singsol=all);
 

\[ y = 2 \arctan \left (\frac {-b +\tan \left (\frac {\sqrt {a^{2}-b^{2}}\, \left (c_1 +x \right )}{2}\right ) \sqrt {a^{2}-b^{2}}}{a}\right ) \]

✓ Mathematica. Time used: 60.123 (sec). Leaf size: 52

ode=D[y[x],x]==a+b Sin[y[x]]; 
ic={}; 
DSolve[{ode,ic},y[x],x,IncludeSingularSolutions->True]
 

\[ y(x)\to 2 \arctan \left (\frac {-b+\sqrt {a^2-b^2} \tan \left (\frac {1}{2} \sqrt {a^2-b^2} (x+c_1)\right )}{a}\right ) \]

✗ Sympy

from sympy import * 
x = symbols("x") 
a = symbols("a") 
b = symbols("b") 
y = Function("y") 
ode = Eq(-a - b*sin(y(x)) + Derivative(y(x), x),0) 
ics = {} 
dsolve(ode,func=y(x),ics=ics)
 

TypeError : < not supported between instances of NoneType and y