halfway merged and pulled?!

Functions/convert_freq_lambda.m

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+%% ============================================================
+%  Wavelength–Frequency Conversion Utilities
+% ============================================================
+
+% Example usage:
+%   f = lambda2freq(1310e-9);              % 1310 nm -> Hz
+%   lambda = freq2lambda(224e12);          % 224 THz -> m
+%   delta_lambda_nm = df2dlambda(224e12, 400e9); % 400 GHz @ 224 THz -> nm
+%   delta_freq_GHz  = dlambda2df(1310e-9, 3.45); % 3.45 nm @ 1310 nm -> GHz
+
+%% ---- Core conversion functions ----
+function f = lambda2freq(lambda)
+% lambda2freq Convert wavelength [m] → frequency [Hz]
+    c = physconst('lightspeed');
+    f = c ./ lambda;
+end
+
+function lambda = freq2lambda(f)
+% freq2lambda Convert frequency [Hz] → wavelength [m]
+    c = physconst('lightspeed');
+    lambda = c ./ f;
+end
+
+%% ---- Differential conversions ----
+function d_lambda = df2dlambda(f_center, d_f)
+% df2dlambda Convert frequency spacing Δf [Hz] → wavelength spacing Δλ [m]
+% around a given center frequency f_center [Hz].
+% Uses first-order differential: Δλ ≈ (c / f^2) * Δf
+
+    c = physconst('lightspeed');
+    d_lambda = (c ./ (f_center.^2)) .* d_f;
+end
+
+function d_f = dlambda2df(lambda_center, d_lambda)
+% dlambda2df Convert wavelength spacing Δλ [m] → frequency spacing Δf [Hz]
+% around a given center wavelength λ_center [m].
+% Uses first-order differential: Δf ≈ (c / λ^2) * Δλ
+
+    c = physconst('lightspeed');
+    d_f = (c ./ (lambda_center.^2)) .* d_lambda;
+end
+
+%% ============================================================
+%  Example section (can be commented out)
+% ============================================================
+
+if ~isdeployed
+    fprintf('--- Example conversions ---\n');
+
+    lambda_nm = 1310;                 % nm
+    lambda = lambda_nm * 1e-9;        % m
+    f = lambda2freq(lambda);          % Hz
+    fprintf('λ = %.1f nm  →  f = %.3f THz\n', lambda_nm, f/1e12);
+
+    d_f = 2000e9;                      % 400 GHz spacing
+    d_lambda = df2dlambda(f, d_f);    % [m]
+    fprintf('Δf = %.0f GHz @ %.1f nm  →  Δλ = %.3f nm\n', d_f/1e9, lambda_nm, d_lambda*1e9);
+
+    % Verify reverse direction
+    d_f_back = dlambda2df(lambda, d_lambda);
+    fprintf('Δλ = %.3f nm @ %.1f nm  →  Δf = %.0f GHz\n', d_lambda*1e9, lambda_nm, d_f_back/1e9);
+end