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%
%    HM690.m  -  B-H interpolation routine
%
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function y = HM690(Bx)
% B-H values that follow are valid for M-6, 29 ga, 90 deg
B=[0 38.7 45.2 52 58 64.5 71 77 81 84 87 90 93.5 97 100 ...
      103 106 110 113 116 135 142 200]*1000;  % Kilolines/sq_in
H=[0 3.1 3.2 3.4 3.6 4 4.4 5.4 6.5 8.5 16.1 32.3 72.7 97 ...
      133.4 174 232 283 333 404 2500 8e3 1e7];  % A_t/in
% Activate to plot B-H curve
% m=15; plot(H(1:m),B(1:m)); grid; % Linear plot
% m=23; semilogx(H(2:m),B(2:m));grid; % 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