fix data type issue if lambda is Float64 but data_type is Float32
fix data type issue if lambda is Float64 but data_type is Float32

dplarson/Mocha.jl,nstiurca/Mocha.jl,nstiurca/Mocha.jl,RatanRSur/Mocha.jl,RatanRSur/Mocha.jl,dplarson/Mocha.jl,JuliaPackageMirrors/Mocha.jl,jeff-regier/Mocha.jl,jeff-regier/Mocha.jl,JuliaPackageMirrors/Mocha.jl