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%
%    Hm27.m  -  B-H interpolation routine
%
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function y = Hx(Bx)
% B-H values that follow are valid for M-27, 24 ga. ESS
B=[0 3 7 20 30 40 50 60 70 80 86 90 95 100 108 120 130 140 ...
150 160 170 180 190 ]*0.0155; % T
H=[0 0.25 0.5 1.3 1.75 2.38 3.25 4.65 6.7 10.4 14 19 32 ... 
50 97 222 460 950 2750 4550 6033 8100 10000]*39.37; % A-t/m
% Activate to plot B-H curve
% m=15; plot(H(1:m),B(1:m)); grid; pause; % Linear plot
% m=23; semilogx(H(2:m),B(2:m));grid; pause; % Semilog plot
n=length(B); k=0;
if Bx==0; k=-1; y=0; end
if Bx<0; k=-1; y=0; disp('WARNING - Bx < 0, Hx = 0 returned'); end
if Bx>B(n); y=H(n); k=-1; disp('CAUTION - Beyond B-H curve'); end
for i=1:n
if k==0 & (Bx-B(i))<=0; k=i; break; end
end
if k>0;
y=H(k-1)+(Bx-B(k-1))/(B(k)-B(k-1))*(H(k)-H(k-1));
else;
end