Re: Rounding off double precision

Bamm wrote:
(snip)

However I have since found where I went wrong. I was using

double precision Speed, Azimuth, V
Azimuth = 90.
parameter(Pi = 3.141592653589793238d0)
V = Speed * cos(Azimuth * Pi / 180.)
print *, V

The problem with the unusually large value of -4.37113886E-06 arose
because I didn't declare Pi to be double precision, even though I
assigned a double precision value to it.

This problem might be more likely to occur to ex-C programmers.

C uses #define is places where Fortran uses PARAMETER,
but #define is typeless.

It might be nice for compilers to give a warning in this case.
There are enough reasons to assign double precision values to
single precision variables that I wouldn't want a default warning
in that case. I don't believe the same is true for PARAMETER.

-- glen

.

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