If else if loop

Hello all, I am trying to make a MATLAB function block in Simulink where in I need a specific spring force (Spring rate x Displacement) for a specific displacement signal. Following is the Simulink figure and the corresponding code in the block.

function Spring_Force = fcn(displacement)

if (0 <= displacement <= 15) % Stroke
    Spring_Force = 10*displacement;
   elseif (16 <= displacement <= 100) % Stroke
    Spring_Force = 18*displacement;
    else
    Spring_Force = 14*displacement;
end

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The problem: The output is always the first statement i.e. - Spring_Force = 10*displacement; even if the displacement signal varies above 15 as specified. It does not consider the elseif and else statements at all. There is no error shown. If I re-write the first statement as Spring_Force = 0*displacement, the output is 0 for that input signal. Can anyone please help on this?

Thank you very much.

Answer 1

[madhan ravi]

function Spring_Force = fcn(displacement)
Spring_Force =  (0 <= displacement <= 15) .* 10*displacement + ...
                (16 <= displacement <= 100) + 18*displacement + ...
                (displacement > 100) + 1 * displacement;
end

[Nimish Iwale]

Thank you very much.

Can you please tell me why have you used - '.*' for the 1st condition and '+' for the rest two?