# plotting when variables are conditional

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Prince Igweze on 7 Nov 2019
Commented: Walter Roberson on 7 Nov 2019
t = logspace(-3,13,100)
for j = 1:100
q = inv((At * Cdi * A) + (t(j) * Ht * H)) * At * Cdi * do
c1(j) = transpose((A * q) - do) * Cdi * ((A * q) - do)
end
m = inv((At * Cdi * A) + (t("C1 = N") * Ht * H)) * At * Cdi * do
depth = 1:50
plot(m,depth)
I want to plot the solution m againt depth
but for the the value of t when C1 is closest to N (i.e 20), and this value changes for each RUN
i believe an if-statement might help me achieve this, pls help
thanks

Walter Roberson on 7 Nov 2019
It looks unlikely to me that c1 will happen to be bit-for-bit identical to any integers.
Will you be wanting to find the index at which C1 is closest to N? Would you be wanting to find the last index at which C1 does not exceed N? The first index at which C1 is at least as high as N ? Do you want to interpolate the index at which c1 exactly equals N, and use that to interpolate a the corresponding t value?
Prince Igweze on 7 Nov 2019
yea, ill like to use the value at which C1 is closest to N, and use the corresponding t value

Walter Roberson on 7 Nov 2019
[~, idx] = min(abs(c1 - N));
t(idx)

Prince Igweze on 7 Nov 2019
thanks but how do i implement this in the plot
Walter Roberson on 7 Nov 2019
[~, idx] = min(abs(c1 - N));
m = inv((At * Cdi * A) + (t(idx) * Ht * H)) * At * Cdi * do;
It seems unlikely to me that you want depth to be your y axes. It seems more likely that you would want
plot(depth, m)