c_1 = 0
c_2 = 0
c_3 = 0
c_4 = 0
c_5 = 0
c_6 = 0
c_7 = 0
c_8 = 0
c_9 = 0
c_{10} = 0
c_{11} = 0
c_{12} = 0
b = 2.6 (slider from 0 to 3.141592653589793, step 0.1)
d(x) = b^(2) / (π^(2) - b^(2)) * sin(π * x)
c: d(0.5)
c_{13} = 0
c_{14} = 0
c_{15} = 0
c_{16} = 0
c_{17} = 0
c_{18} = 0
c_{19} = 0
c_{20} = 0