# Use linspace without scalar input?

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Andrew Poissant on 29 Aug 2017
Commented: Andrew Poissant on 29 Aug 2017
I want to use linspace that goes from two non-scalar terms. Is there a way to use linspace with specified number of points, n, for decimal values for inputs? Example code is below for what I am looking for.
x = 0.01;
y = [1.01, 3.01];
n = 10;
dxy = linspace(x, y, n);

the cyclist on 29 Aug 2017
Rather than telling us an input syntax that clearly doesn't work, it might be better to tell us what output you are hoping to get.
It seems like you are trying to over-specify what you want to get.
KSSV on 29 Aug 2017
n cannot be a decimal.....it should be an integer.
Andrew Poissant on 29 Aug 2017
My apologies. n will be an integer since it is the number of points. I want to use decimal values for x and y. So part of the output I am looking for would be dxy = [0.01 0.11 0.21 ... 1.01; 0.01 0.11 0.21 ... 3.01]. Hope this makes things clearer.

Guillaume on 29 Aug 2017
Edited: Guillaume on 29 Aug 2017
x = 0.01;
y = [1.01, 3.01]; %would be better as a column vector as you wouldn't to tranpose it in the arrayfun
n = 10;
dxy = cell2mat(arrayfun(@(e) linspace(x, e, n), y', 'UniformOutput', false))
Or using a loop:
x = 0.01;
y = [1.01, 3.01]; %would be better as a column vector as you wouldn't to tranpose it in the arrayfun
n = 10;
dxy = zeros(numel(y), n);
for row = 1:numel(y)
dxy(row, :) = linspace(x, y(row), n);
end
or using Jan's idea but with R2016b or later syntax:
x = 0.01;
y = [1.01, 3.01]; %would be better as a column vector as you wouldn't the transpose in the calculation of dxy
n = 10;
dxy = (0:n-1) .* (y'-x)/n + x

#### 1 Comment

Andrew Poissant on 29 Aug 2017

Jan on 29 Aug 2017
Edited: Jan on 29 Aug 2017
x = 0.01;
y = [1.01, 3.01];
n = 10;
dxy = [linspace(x, y(1), n); ...
linspace(x, y(2), n)];
Or:
Step = repmat((y(:) - x(:)) / (n - 1), 1, n);
Step(:, 1) = x(:);
dxy = cumsum(Step);

#### 1 Comment

Andrew Poissant on 29 Aug 2017
How would I generalize the first option if I have many values in the y vector? I tried the following:
for i = 1:length(y)
dxy(i) = linspace(x, y(i), n);
end
but got the error "Subscripted assignment dimension mismatch."

Stephen Cobeldick on 29 Aug 2017
Edited: Stephen Cobeldick on 29 Aug 2017
An efficient general solution for any size y using linspace and bsxfun:
>> x = 0.01;
>> y = [1.01, 3.01];
>> n = 10;
>> bsxfun(@plus,x*linspace(1,0,n),bsxfun(@times,y(:),linspace(0,1,n)))
ans =
0.010000 0.121111 0.232222 0.343333 0.454444 0.565556 0.676667 0.787778 0.898889 1.010000
0.010000 0.343333 0.676667 1.010000 1.343333 1.676667 2.010000 2.343333 2.676667 3.010000
MATLAB versions with implicit expansion could probably do this (untested):
x.*linspace(1,0,n) + y(:).*linspace(0,1,n)

#### 1 Comment

Andrew Poissant on 29 Aug 2017
Thank you!