In the Matlab I have the following equation, which gives me a, b, c and d coefficients.

gaussEqn = 'a*exp(-((x-b)/c)^2)+d';

[fittedModel, gof] = fit(sensData(:, 1), sensData(:, 2), gaussEqn, 'Start', startPoints);
a = fittedModel.a;
b = fittedModel.b;
c = fittedModel.c;
d = fittedModel.d;

How can I do the same in C# using math libraries? The equation is not exactly gaussian, but contains an extra d coefficient. But I will be happy even to calculate a, b c only based on gaussian equation.