how to use math.log10 in sympy-CodePudding

I have a problem whit sympy, i need to solve a system of two equation : B1=2.51/(Re(f^(0.5))) f=(1/(-2*log10((epsilon/D/3.7) B1)))^2 I tryed using sympy, numpy and fsolve, but there is a problem with the use of math.log10, that returns a float:

from sympy import*
import math
def f_cole(Epsilon, D, Re):

#Fattore di attrito Equazione di Colebrook per flusso turbolento

B1,f=symbols('B1,f')
eq1 =Eq(( 2.51 / (Re*(f**0.5))-B1),0)
eq2=Eq(((1/(-2* math.log10((Epsilon/D/ 3.7) B1)))**2 -f),0)

solveset((eq1,eq2), (B1,f))

return(f)

That returns :

TypeError: can't convert expression to float

CodePudding user response：

You cannot mix functions from module math with sympy expressions. Functions from math expect floats as input, not expressions.

Instead, use sympy.log.

import sympy

x = sympy.Symbol('x', real=True)
print('log(x):       ', sympy.log(x))
print('log(exp(x)):  ', sympy.simplify(sympy.log(sympy.exp(x))))
print('log10(x):     ', sympy.log(x, 10))
print('log10(10**x): ', sympy.simplify(sympy.log(10**x, 10)))

Output:

log(x):        log(x)
log(exp(x)):   x
log10(x):      log(x)/log(10)
log10(10**x):  x