Tri color gradient issue

Hi,

I am trying to build an application where tricolor gradient is used but i found abrut change in the color. But there is smothness in the case of 2 color gradient. So please help me out to create an tri color gradient with the smothnes of all three color.

Note: In image you can see a strip of yellow,green and black color.I want, there is smothness when two color intercept